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How Do I Filter Phone Calls on a Land Line? 181

An anonymous reader asks: "I have a telephone on a plain old land-line, with the option of subscribing to caller-id. I would like to filter incoming phone calls, diverting them to either the handset or answering machine, based on whether the caller-id matches a list of trusted phone numbers. Considering that many of today's land-line telephone handsets can display caller-id and store a list of favourite phone numbers, I don't think this is technologically difficult. AI am not interested in: subscribing to a service provided by my telephone company. I would prefer the filtering occurred on my side of the phone line, or implementing a software solution on my PC. Frankly, that is overkill, and I don't want my PC turned on permanently. I would prefer something like a small, solid-state hardware device. Is there any such thing available?"
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How Do I Filter Phone Calls on a Land Line?

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  • There is (Score:5, Funny)

    by Anonymous Coward on Monday June 19, 2006 @08:50PM (#15565778)
    I beleive it's called a "wife". However, it's very very hard to pick these things up at a hardware store, and you can't get them off the internet (or at least the internet versions don't handle english language filtering all that well). I'd suggest that looking for more information on wives from slashdot is probably a waste of time.
  • by 0racle ( 667029 ) on Monday June 19, 2006 @08:51PM (#15565783)
    An answering machine. Don't answer till you know who it is, and if they don't leave a message you probably didn't want to talk to them anyway.
    • A wise man once said as simple as possible and no simpler. I like this solution :)
    • by Alien Being ( 18488 ) on Monday June 19, 2006 @09:24PM (#15565898)
      Not quite right. I think the real question is which answering machine has the ability to ring or not-ring based on caller-id info. I wish my own answerer could do that. It should have these options to control whether the phone rings:

      Ring/don't ring for blacklisted callers
      Ring/don't ring for whitelisted callers
      Ring/don't ring for new but identified callers
      Ring/don't ring for unidentified callers

      It should have similar modes controlling whether or not the machine will accept a voice message. That should all be simple to implement in a device that connects like a regular phone (in parallel). When reviewing the incoming calls, it should be a one-touch operation to specify how the machine should handle future calls of the same type.

      The super-duper version should have the ability to sit between the phone line and other devices (series) and use a speech synthesizer and recognizer (or dtmf decoder) to allow control from regular phones throughout the house. e.g. A call comes in, the phones give a single short ring as the machine announces itself to the caller. If a person picks up a phone, the machine tells him whatever it knows about the call and asks whether to hangup, connect, or take a message.

      • Talking Caller-ID (Score:4, Informative)

        by Jetson ( 176002 ) on Tuesday June 20, 2006 @03:54AM (#15567252) Homepage
        which answering machine has the ability to ring or not-ring based on caller-id info

        The Caller-ID information is sent between the first and second ring, so the only way to avoid ringing is to drop the first ring 100% of the time. On the occasions where you do want to talk to someone, the time left to get to the phone is that much shorter.

        I have an AASTRA talking Caller-ID box in my house. It does a great job of managing the phone. If the caller has intentionally blocked their Caller-ID information then it automatically answers after one ring and tells them I don't accept blocked calls (which are inevitably from telemarketers) and they should call back with Caller-ID enabled. For the rest, it speaks the phone number so I know who it is before I get to the phone. If it's someone I don't want to talk to then I just let it ring until the answering machine cuts in. It supports blacklisting so that people who annoy me don't even get to leave a message. One interesting feature is that I can record a short audio clip and have it matched to a specific name or number so that it will play that audio clip instead of speaking the number. That's a great help with things like payphones which I will always want to answer no matter what the number is (my telco sends "payphone" as the Caller-ID name).

        • I inform the person that if it's a telemarketer and they continue to talk to me anyway, that the fee will be $250. That way, when my friends need to call me from a payphone, they're not screwed. About once every four months a telemarketer gets ballsy, but on the other hand, so far I've scared two supervisors into actually paying out the fee, which pretty much guarantees that firm will never call me again.
    • I hate that. I hate talking to answering machines and usually won't leave a message unless I have already tried calling several times with no answer and have no other way to contact the person. If you do that you are telling me that your time is more important than mine - I have to talk to a machine so you don't have to risk hearing from someone you don't want to talk to. If it's a temporary thing while you change your phone number after being harassed, that's one thing. As a permenant solution, it's qu
      • by LordNightwalker ( 256873 ) on Tuesday June 20, 2006 @01:16AM (#15566819)

        "Hi, it's Mike. I'm not in, so leave your message after the beep" costs you less 5 seconds of your life. If the answering machine is set to pick up immediately, it will even *save* you time, because the machine will have picked up before I have the time to walk over to the phone and pick it up manually.

        On the other hand, you might be that pesky asshole I don't really want to talk to. You know, the one that won't shut up, the one I can't possibly end a phonecall with in less than 20 minutes without being rude.

        So let's do the math again:

        • You call me, leave a message after the beep. You lose: 30 seconds total, 45 tops.
        • You call, I pick up, you're the talkative asshole. I lose: at least 5 minutes, possibly half an hour or more.
        My time doesn't have to be more important than yours to justify my screening of the calls; I stand to lose more time than you by picking up the phone. You can whine about it all you want, that won't change the facts.

        Besides, my time might very well be more important than yours, and probably is. Remember that you're the one picking the time of the call, not me. You time the call to coincide with a moment you're not doing anything important anyway, unless it's an emergency call. Chances are I'm actually in the middle of something. Are you trying to tell me that whatever it is you want to tell me is more important than anything I might be doing at that time?

        If whatever you want to tell me is important enough to interrupt my shedule for, it's important enough to leave a message for. If you can't be bothered to interface with a machine for 20 seconds to help me manage my time, I can't be bothered to interrupt my shedule to talk to you.

        • Oh, that doesn't account for some of the terrible voicemail systems offered by phone providers. Some of it goes on for 1 minute, asking you to key in numbers to leave a message, or you can type in your phone number so, they don't have to actually redial it. It's a real pain. I just want to leave a message. As a side note, if you don't want to leave a message, there's always the double ring, right before the answering machine picks up. Usually when the double ring hits, if I don't want to leave a messag
      • If you do that you are telling me that your time is more important than mine - I have to talk to a machine so you don't have to risk hearing from someone you don't want to talk to.

        Is that a troll? Yes, I'm fairly certain it is. It doesn't send any such message. The phone company paid a lot of money back when the phone system was first established to drill into the public that ignoring a ringing phone under any circumstance (such as already having visitors) was unspeakably rude. This attitude seems to li
      • Remember, whoever you call may actually feel they own the phone, as opposed to their phone owning them. It's their choice as to how they want to treat calls at any given time. I'm basically asking to intrude when I call someone, after all...

        The same principles apply when dealing with people ringing my doorbell.
      • You're the one who's interrupting my life by calling. If you don't want to talk to me that much, don't call. Send an email or something (or don't).
    • It goes both ways. (Score:2, Insightful)

      by r00t ( 33219 )
      I probably don't want to talk to a person who screens calls like that.

      I certainly won't talk to a machine. I might stumble over my words. Am I supposed to have a ready-made speech for you to record? It's not as if I could call back later to delete the message I left, or could determine if you got the message.

      I may be paying long distance charges.

      So, screw you. I have better things to do. I could talk to some nice and friendly people.
      • by jon doh! ( 463271 ) <> on Monday June 19, 2006 @11:40PM (#15566450) Homepage it that hard to say "it's me [$yourname], its [not] important, call me back."?
      • Am I supposed to have a ready-made speech for you to record?

        "Dude. It's r00t. Call me."

        I may be paying long distance charges.

        Even better. Now they have to call you back, and they pay the long distance.
      • by lawpoop ( 604919 )
        "Am I supposed to have a ready-made speech for you to record?"

        Look, this isn't a Senate hearing. Just say who you are, when (approximately) you are calling, and what you are calling about, and what I should do in response to your call (i.e. call the police, call back immediately, call back when I get a chance, wait for your call...)

        Something like,
        Hey, it's r00t, it's about five-thirty -- I was just calling to see if you wanted to go to the game on Saturday... I had an extra ticket... Gimme a call when y
        • I could be calling to communicate or to socialize. Either way, I'm going to take a rather negative view of the answering machine. Unless I really need to talk (calling my boss, family member died, etc.) I'm just going to give up. Screw you.

          If you won't pick up the phone, why did you give out the number in the first place? That was rude. You faked me out.

          • by lawpoop ( 604919 )
            "If you won't pick up the phone, why did you give out the number in the first place? That was rude. You faked me out."

            I certainly wouldn't have given you my number to be at your beck and call at any time you please. When you call, I'll pick up if I'm not busy and I feel like socializing. Since you probably have no idea what I'm doing at the time when you call, you wouldn't know whether or not it's a good time. Maybe I'm the the shower, in the middle of a task, having an argument with my spouse, or even d
            • "I certainly wouldn't have given you my number to be at your beck and call at any time you please."

              Fine. I can understand that: I do not usually give out my pnone number. At the moment my phone lacks an incoming number.

              If you choose to give out your phone number, then I nearly expect that you will be at my beck and call any time I please. You made the choice to give out your phone number. Live with it. It's rude to fake people out.

              I can understand not picking up. You can just let the phone ring foreve

              • by lawpoop ( 604919 ) on Tuesday June 20, 2006 @11:25AM (#15569544) Homepage Journal
                "If you choose to give out your phone number, then I nearly expect that you will be at my beck and call any time I please. You made the choice to give out your phone number. Live with it. It's rude to fake people out. " You really think that when someone gives you their phone number, they are really expecting to become your personal genie ( "You rang, master?" ) just because they gave you seven digits? I think you have an unrealistic perception of what relationship you are establishing when you get a phone number.

                I think you are probably the only one getting "faked out" when people hand you their number. I haven't met anyone who thinks like you.

                So you don't like call screening. You don't like talking to machines and leaving messages. Can you imagine that you might actually need to leave a message for someone? That an answering machine might actually convey information?

                You do realize that you aren't actually talking to a machine, right? That box isn't acutally listening to you, you know -- it's just a recording device to give a message to the intended recipient. You might think of it as a delayed conversation, or a verbal letter -- a 'voice mail', so to speak.

                When you were young, you lived in a different world. When the phone rang, you had to rush to wipe your ass so you could pick it up -- if you missed the call, you would have no idea who called, why, or how important it was. Nowadays, we have caller id, answering machines, and voice mail. We don't *have* to rush, so why should we? Why should I develop hemmoroids hurrying my bowel movements because Right Now works for you?

                You took the damn time to call, you must have had something to say, even if it's just "hey, calling to chat" so leave a fricking mesage!! I've got better things to do than wait around for people to call.
              • by Sloppy ( 14984 )

                If you choose to give out your phone number, then I nearly expect that you will be at my beck and call any time I please. You made the choice to give out your phone number. Live with it. It's rude to fake people out.

                The problem here is due to different interpretations of what a phone number is for. Some people give out phone numbers so that they can be communicated with. You think people give out phone numbers so that they can be communicated with interactively.

                Screening calls is rude. I avoid calling

                • It sure is odd to be giving out a number if you don't want interactive communication.

                  For non-interactive communication, we have the written word. These days it doesn't even cost you a stamp. The sender gets to compose a message at leisure, rewording the message until it is just right. Pictures (worth 1000 words each) can be included.
              • You can explain and wax poetic about your expectations and preferences all you want, but it doesn't change one simple fact: my phone, my rules. When you call me, you are asking (OK, DEMANDING, in your specific case) to interrupt whatever I was doing. When I glance over at Caller ID and see it's a number I don't want to talk to right now, I just do nothing. It's a great service, I don't have to screen any calls, and those who leave voicemail usually are calling me for a reason these days.
                • Your phone, your rules. Cool.

                  Warn me about your behavior so that I won't bother to keep your number. Better yet, just don't give out your phone number. Keep it unlisted and don't offer it.

                  I don't like to interrupt what I'm doing either... so I don't give out a phone number.
        • Only on Slashdot must nouveaux-luddite people be instructed how to leave messages on answering machines. It's not 1965, people.
      • I probably don't want to talk to a person who screens calls like that.

        And judging from your attitude, you're probably the reason they screen their calls like that, so I doubt they want to talk to you. You're happy, they're happy, the world just became a better place.

        I certainly won't talk to a machine. I might stumble over my words. Am I supposed to have a ready-made speech for you to record?

        Well, did you have a ready-made speech for the occasion where I actually pick up the phone? No? Damn, h

        • by r00t ( 33219 )
          When talking to a human, I can hear the response. I immediately know if my words have been misinterpreted. The machine faithfully records something that may be taken wrongly, perhaps with disasterous consequences.

          A human doesn't need a ready-made speech. There is interaction. The feedback helps to form the message.
          • What about leaving a written note for someone? "Hey Jeff. Dropped by, but you weren't in. Wanna meet for lunch tomorrow? -r00t" There's no immediate feedback, there's the risk of misinterpretation, etc etc.

            Or are your conversations more like this:

            r00t: "Begin msg. 'Hey Jeff. It's r00t.' End msg."
            Jeff: "Begin echo. 'Hey Jeff. It's r00t.' End echo. Begin msg. 'Hi r00t, long time no hear, what's up?' End msg."
            r00t: "Begin echo. 'Hi r00t, long time no hare, what's up?' End echo. Begin msg..."
            Jeff: "Begin co
            • When leaving a written note, I get time to think it over carefully to minimize the risk of misinterpretation. I don't get that with an answering machine unless I carefully rehearse in advance.

              Not being a major phone user, I don't have a fill-in-the-blank speech as a reflex action. I'm sure a salesman has something ready, but I'm no salesman.

      • I certainly won't talk to a machine. I might stumble over my words. Am I supposed to have a ready-made speech for you to record? It's not as if I could call back later to delete the message I left, or could determine if you got the message.

        Stumble over your words? It's a machine. How would it be any different if you were talking to the person? "Hi, it's [$name]. [if $subject then say "Calling about $subject"] It's [if !$urgent say "not"] urgent. You can call me back at [$phonenumber]. Bye!"

        I may be paying l

      • I hate leaving messages. However, I have found this simple prepaired message quite effective. "Hi, this is [my name] gimme a call back. Thanks."

        If you can't be bothered to do that much then screw you.
    • If i ever called someone who did this, I would say "James here, call me back, bye" really quickly before they could pick up the phone. And then when they did, i'd let it go to my answering machine and call them back again and do the same thing.

      But only if it was raining outside and I had nothing else to do :)
  • by Trialpha ( 712774 ) on Monday June 19, 2006 @08:56PM (#15565800)
    • Nice. Even I want one of those, and I don't even have a land line!

    • Wow. I don't think I have ever seen an AskSlashdot question more completely and totally answered than your response. Bravo.
      1. Block anonymous and unidentified numbers, while allowing all others;
      2. Block up to 175 numbers, area codes or prefixes

      For 100 bucks, that's a bargain, considering that the phone company will charge you separate monthly fees for the ability to do either of those things. (Not including blocking by area codes or prefixes, since they don't offer that AFAIK)

      If you need/want those services, that box will pay itself off in 2~3 years.

      If it's simple enough, I might get one for my parents.
      They loved the tele-zapper.

    • Cool idea, but bad user interface.

      It should have five buttons: one button labeled "BAD NUMBER" and a different button labeled "GOOD NUMBER". A scroll up and down button and a "FORGET NUMBER" button would complete everything it needs. No "save", no "select", no "menu", no "timer", no "dialing". It doesn't need time and date (good god, not every device need a fracking clock these days!,) and it doesn't need to be "preprogrammed". It just has to route junk calls to the answering machine, not "manage my

      • You obviously don't have one of these, I do. Please educate yourself on how the unit works and what the buttons do before you spout off that it is "bad". Your entire post is a mass of inaccuracies and misconceptons on what the device is capable of.

        Just as one example, there is more to a caller then "good number" or "bad number". There are actually 3 choices on the machine: 1= do not send to answering machine and do not ring the phone. This would be the ex-wife option. 2= send to answering machine but do not

        • Please educate yourself on how the unit works and what the buttons do before you spout off that it is "bad".

          I'm afraid you have fallen completely into the trap of "accepting badness". (Don't blame yourself, bad UI is standard practice in the computer industry, honest.)

          The device itself is not bad, and I did not say the device was bad. The device sounds like a wonderful piece of technology that could solve a real problem for most people. (By the way, if you work for "ASPHALT PAVING" and you called my

    • This is quite a first I've seen on an Ask Slashdot. Someone's question is a very detailed list of the specifications of what they want a technological solution for. That's almost a miracle in itself that the question made sense, was slightly challenging to answer and research, and didn't involve asking for legal advice. Most amazing of all was that someone actually provided a link to a device to purchase that seems to do exactly what was asked for and more. Bravo!

      OK, everyone, the Ask Slashdot category
  • by MBCook ( 132727 ) <> on Monday June 19, 2006 @09:00PM (#15565811) Homepage

    OK, you have a couple of options as I see it.

    First would be to set up some kind of PBX. It's a little complex, but it would work. You could use Asterisk (I think that is what it's called) and some hardware (since I think it was designed for VOIP) and do it that way.

    The more fun (in my eyes) and complicated way is to build it yourself. You could do this with a PIC micro-controller (or similar). You could put the little box you would make at the phone entry point of your house. When the phone rings you let the first ring through (so you know someone called). Caller ID is transfered between the 1st and 2nd rings so that is when the MCU picks that up. Based on that, it can power a double pole double throw relay. In the normally closed position the phone signals are routed to your house wiring. When a "bad" caller ID is encountered it simply powers the relay switching the phone line from being connected to the phones to the answering machine. Of course the answering machine could be anywhere if you can isolate it's phone jack from the rest (shouldn't be too hard).

    Now there are a few little things to take into account here. First is that you may want to generate a ring for the answering machine so that it picks up on the 4th ring (or whatever) instead of the 5th because of the "lost ring". Second is that if you automatically send people to the answering machine unless the right caller ID comes across (i.e. the answering machine is in the normally closed position) then you'll need to make sure you have a way to force the relay to switch. You would want this even if you decide to pick up a call from the machine. When the main wiring is disconnected you could monitor the wiring to see if anyone picks up (you'd have to power it probably) and switch the relay if that happens. That way any time you pick up the phone you will always get the dial tone/caller. Having the relay connect you to the phone line in the normally-closed position is an important idea because you want it to be safe and let you use the line during a power outage.

    It'd be a very cool project. You can find bits about how to do it on the web. For example, I once saw something about a guy who built his own TTL PBX. That project (which was rather well documented, as I remember) would be a gold mine for you.

    If you do it, make sure to write it up and post it. I'd love to read it and I'm sure others would too.

    • To lead off, a suitable software/computer prototype can be made with a computer and modem. Most modems can be put into a "report caller ID" mode. Make some simple C software to listen ot the serial port, and control the relay going to the regular phones using the parallel port.

      Once you have a suitable software prototype, use a PIC or AVR to talk to the modem and control the relay. At this point you've got an easy, simple system that does what you want it to do - but you've probably got to update it te
      • by MBCook ( 132727 ) <> on Monday June 19, 2006 @10:21PM (#15566138) Homepage

        I like the idea of keeping the phone line connected all the time by default, and it makes some other things easier. That said, I bet you could easily make the circuit to eat that first ring so it doesn't go through to the house wiring. You could eat ALL rings and just re-generate them yourself on the outputs (house and answering machine).

        Heck, you could use a voltage comparison to trigger a disconnect so when the phone rang the line is temporarily disconnect for the duration of the ring signal. The the right sized capacitor to absorb the spike that did get through and a transistor to let you turn that feature on and off (so you can let rings through if you want) would probably do it.

        As for how to get the data on and off, there are a few ways. You can go the program the MCU way, but that's annoying as you mentioned. You can make the MCU take direction form a serial port so you can program some flash memory that holds the list. But the easiest way is that it's not too hard to interface to a SD card or similar. You can buy very simple devices that let you access them with just a serial line or two. Put the list in a text file with a simple format (first line is the number of entries, after that each line is a valid number, sorted to allow for binary search) and you can update it trivially without having to reprogram and such.

        That said, as the parent poster said you could use a Rabbit or some other MCU with easy external access. There are ethernet (often an add on you can buy for another MCU), you could use serial or USB or BlueTooth. Plus there is always the LCD/buttons approach.

        Heck, program it with your phone. Pick up the phone and dial a magic sequence (###) or press a button then pick up the phone and you can do simple button combinations to program it. When in "magic mode" press 1 and then a 10 digit number to add it to the list. Press 2 and then a 10 digit number to remove it from the list. Both are confirmed with a simple tone. Press 3 then a 10 digit number to find out if it is in the list or not (one beep yes, two no). You could add other features later this way too. A simple way to turn on/off the filter for when you are expecting a call but you don't know who it will come from, or you want to go into "silent mode" to watch a movie where EVERYTHING goes to the machine.

        You could do other fun stuff. If someone calls from a blocked number and gets the machine, you can monitor that with the PIC. If you detect they press the magic button sequence (44666, spells "HI MOM") then the PIC generates a ring on your phone. This could be used for emergencies. Then you just pick up and the auto-detect I mentioned earlier connects you and you take over from the machine.

        The only complication I can see is the issue of how to handle call waiting, but you can avoid that just by turning it off.

        I gotta say, the more I write about this the more fun it sounds. Too bad I have no use for it or time to work on it right now.

      • Caller-ID uses Bell 202 modem protocol, which is a simple 1200 bps FSK scheme. You could decode that in software or use a simple FSK demod circuit. It's 1200 Hz for Mark and 2200 Hz for Space.
        • Caller-ID uses Bell 202 modem protocol, which is a simple 1200 bps FSK scheme. You could decode that in software or use a simple FSK demod circuit. It's 1200 Hz for Mark and 2200 Hz for Space.

          Of course. But would you rather spend $20 on an external modem with all that (and more) built in, or would you rather spend hours/days building and troubleshooting a telephone interface, demodulator, and firmware for it? For a one-off I don't see the advantage.

    • Asterisk will do what you want. You can set up rules in your extensions.conf file to filter on the incoming caller id. Send everything unknown to voicemail, and you can create a list of known numbers that will be forwarded to your phone. I'm running it at home now and it rocks.

      If you want an easy way to get started, search for Asterisk@home. It's a distro that just wipes the box clean and installs linux with a fully functioning Asterisk install. About the hardest part of getting it set up is figuring o
    • While that might be fun, you can get quite a bit of of those features with a "Virtual" PBX or virtual attendant. I know that the poster did not want to pay for such a service, but it's dirt cheap. They have services that work with VOIP or POTS and give you all the possible options of a PBX. You can set up your cell phone as a extension, etc., auto call routing, MMS message the incoming phone number to your mobile, assign business rules to number types, etc.

      Asterisk is really cool but it's overkill for on
    • Based on that, it can power a double pole double throw relay. In the normally closed position the phone signals are routed to your house wiring. When a "bad" caller ID is encountered...

      Wow. I totally misinterpreted that. It wasn't 'til the next sentence that I found out the "bad" caller wasn't getting 120V house current sent to his handset. :-(
  • Build your own! (Score:5, Informative)

    by ResQuad ( 243184 ) * <slashdot&konsoletek,com> on Monday June 19, 2006 @09:04PM (#15565828) Homepage
    Well the obvious answer (at least to me) is Asterisk []. If you don't want a "computer running all the time" build a small box, well.... tuff. Think Mini-ITX []. You can put a small HD in in, and put it in a small case. If its only "diverting" calls it doesn't need much power or storage space at all and wouldn't draw much power (also, if you do it right - it could be all passive cooled).

    Also - I'm sure no one wants to spend _that much time_ setting up Asterisk, so use TrixBox [] (Formely Asterisk@Home) instead.
  • by TheCodeFoundry ( 246594 ) on Monday June 19, 2006 @09:11PM (#15565850)
    Microsoft released a 900MHz cordless phone back in late 1998 that had all the features you want, plus more. You could create a whitelist in the software and any phone call that wasn't in the whitelist wouldn't even ring the handset, but get diverted straight to voice mail. The phone supported voice dialing, multiple voice mailboxes, personalized rings and greetings based on the Caller-ID number. The software would automatically divert or block Caller-ID blocked incoming phone calls. The software even imported your phonebook from Outlook Express/Outlook.

    Ok, granted, the phone was 900MHz, was quite bulky and the batteries were less than optimal. The one feature that this phone had that none (except PBXs) have had since, was total control of the hardware ringer. Because you had total control of the ringer, features became available (and controllable via software) that would allow you to force select incoming calls straight to voicemail or DND without ever being distracted by the ring. Of course, this product was soon killed and all support for updates to the software quickly killed, too.

    • I love 900mhz phones. They don't get interference from Wifi.
      • Cordless Phones (Score:2, Informative)

        by Kadin2048 ( 468275 )
        Just remember that anytime you're talking on a cordless phone, you're using a radio transmitter. While that might seem like a painfully obvious thing to say, it's amazing how many people don't get the connection between "cordless telephone" and "anyone with a scanner can hear everything I'm saying." If you don't believe me, find any good radio that has wideband receive and try searching from around 46.6-50 MHz for the older phones and 900-928 MHz for the new ones. I don't have a receiver that goes to 2.4GHz
        • Sure, I'm fully aware of that, and I don't discuss sensitive information over the phone.

          Remember always that the point isn't that we necessarily want everything we do to be private, but that we want to have the option of privacy. If the government is snooping, that option is gone. If a neighbor is snooping, it's probably my own fault and I probably thought about that ahead of time.
  • Handset. (Score:5, Insightful)

    by jfisherwa ( 323744 ) <jason,fisher&gmail,com> on Monday June 19, 2006 @09:13PM (#15565860) Homepage
    The cheap Uniden dual-handset receiver that came free with my SunRocket service has a built-in phonebook, complete with user groups and different ring-tones. Set the default ring-tone to nothing/one quiet beep and put everyone you know into groups with a real ring.

    No PBX, no software and service independent.
  • since the poster wants to divert a "trusted" number to the handset, I assume he/she is there to answer the phone. therefore, reading the display on the phone, or your TV, or your PC, depending on what you plug the phone line into, is a good choice.
  • by ShyGuy91284 ( 701108 ) on Monday June 19, 2006 @09:59PM (#15566045)
    Hook it up to a Linux box, and..... Yeah, that's all I've got.... It's probably possible though with the right kind of modem hardware and drivers.
  • ISDN (Score:3, Funny)

    by jaredmauch ( 633928 ) <> on Monday June 19, 2006 @10:02PM (#15566056) Homepage
    What you want is to convert your home line to ISDN and use an old motorola BitSurfr device. You hand the calls over to the POTS ports on the device, and you can program it with AT commands. I think you can only set a small number of blacklist caller-id, or whitelist caller-id (i think 10) but it will serve as a nice filter. This will do what you want, and they can get dumped or a busy before the phone even rings.
    • That reminds me. I used to have an ISDN and I had a nice adapter from US Robotics that gave me an ethernet interface to connect my computer to. This made it trivial to share the connection with my house. My service was terrible (and expensive), but the "modem" was nice.

      Now here is the fun part. There was a little utility that US Robotics made that was free. It would sit in your system tray and show you the status of each B channel (data/voice/none). Best of all, the source was available so you could do it

  • Vgetty (Score:2, Informative)

    by mazarin5 ( 309432 )
    I had set up vgetty to answer calls after a number of rings that was based on the caller-id information, but that requires a modem whose voice capabilities are supported on linux. The idea was that 'Unknown Caller', etc. went straight to the voicemail, but everything else was allowed to ring four times. It's a simple and proven method.
  • Our solid state answering machine has the option of diverting calls straight to voicemail based on caller ID, making different ringing tones, and so on. It's years old and no longer on sale, but you'll probably find plenty of others still around that can do the same things. Personally I like sending "caller ID blocked" and "unknown" straight to voice mail...
  • by Anonymous Coward
    What happens if someone on your whitelist is in some sort of emergency that forces them to use a phone that's not on your whitelist? Do you still want that urgent call that to go to the machine?

    Personally I'd perfer not to ever have to answer unsolicited calls, and I'd also like the option of silencing the ring from certain callers at various times of the day. For example, nothing but "work" should ring my phone before 8am, nothing but "that girl I'm stalking" should ring my phone after 8pm, and absolutely
    • by Migraineman ( 632203 ) on Monday June 19, 2006 @11:16PM (#15566350)
      If it's truely important, the caller will re-dial after hanging up on your answering machine's greeting. Works fine.

      Honestly, the "what about emergencies" arguement is as badly abused as "think of the children." My telephone is a resource for *my* convenience, paid for by *me.* If someone calls while I'm eating dinner with my family, the call is allowed to roll-over to the answering machine. If there's an immediate call-back, I'll probably interrupt what I'm doing. Somebody screaming into the answering machine in the next room would be a good clue too. Everything else gets done on *my* schedule.

      It used to be that receiving a telephone call was a big deal - think back to the early 1900's. Nobody had phones. If somebody called you, there was probably large expense (money, time, effort) to place the call from the other end. That expectation persists to today, in spite of the ubiquity and low-value of most phone calls. The phone companies go to great lengths to maintain this perception of "high priority interrupt." They're in your face, and they want to stay there (but that's a completely different rant.)

      Think of the children. They're busy eating their dinner and experiencing some family time. Call back later. (To address the original poster: get an answering machine; learn to use it; don't let the phone rule your life.)
      • Look, maybe this doesn't happen to folks very often, but as someone who doesn't currently own a cellphone and uses public transportation and payphones quite a bit it is a valid scenario:

        you're stuck somewhere and the last bus has already run it's route. It's cold or rainy and you've already walked five to ten miles and are feeling really tired/hungry and like the world doesn't give two shits about you. you're down to your last fifty cents and you've decided to call one of your so-called friends that you t
        • yet leaving the line open for our friends and family that might be on payphones or in unusual situations and in dire need of our help

          So you want people to put up with the certain daily annoyance of telemarketers (new ones will call regardless of how stern you are with previous ones) on the slight chance that we have a deadbeat friend who might have to spend a night outdoors? Even in your contrived scenario, nothing is stopping said deadbeat from leaving a message with his location and situation, then rep

        • Easy enough with an asterisk box to program in an emergency over-ride code that you let's authorised people over-ride the standard call-handling.

          For example, there is no problem defining a dialplan that, if someone calls you and enters 31415 or whatever at the "leave a message" prompt, skips the mailbox and rings every phone you posess until someone answers.
        • Thank you for demonstrating my point. You've created a contrived and improbable scenario where an "important call" might show up demanding your attention. Having swallowed the "importance of the call" rhetoric hook, line, and sinker, you're now prepared to alter your life behavior in order to service the telephone. Answering the phone shouldn't automatically be your highest priority in life. Sooo, in your "valid scenario" above, do you spend all your time hovering over the phone waiting for the "might b
          • My pet peeve is the phone call that gets through in the middle of a meeting forcing you to sit and wait while some ass-hat chatters on about "the game" or whatever.

            The point is, what is more important to you? The person who is face to face with you or the lazy sot who can only be bothered to call. We've totally reprioritised our lives so that the disembodied voice of someone with your phone number deserves more attention than an actual person. More and more, I ignore the phone, or use it to set up face-tofa
        • Should we stay home all of the time too so we're there to answer when this one in a million phone call occurs?
    • What about emergencies?

      Just have your answering machine's message say,

      Hello, you have reached _______. If this is an emergency, hang up and dial 911. Otherwise, leave a message. *BEEP*

  • by Bitsy Boffin ( 110334 ) on Monday June 19, 2006 @11:36PM (#15566433) Homepage
    1 sound muffled box containing
        phone with answering machine
        digital camera
        laptop with OCR and RDBMS software
        robotic hand

    have the laptop listen to the microphone for noise (phone ring), the robotic hand should then hit the button on the camera which takes a picture of the LCD display on the phone showing the number, the image is transferred to the OCR software which returns the number, lookup the number in the RDBMS, if it's ok the robotic hand pushes open the lid on the sound muffled box "letting the ring out", if it's somebody you really don't want anything to do with the robotic hand lifts the phone and hangs up, in all other cases the phone is left to ring in the sound muffled box until the answering machine picks up.

    Problem solved.
  • by boldtbanan ( 905468 ) on Monday June 19, 2006 @11:45PM (#15566471)
    My AT&T E5965C does exactly that. It's about $120 if you can catch it on sale.

    Here it is at Amazon []
  • by Eil ( 82413 )
    I could have swore that some modems that I bought back in the day listed "Caller ID" as one of their features in the specification on the packaging. My question is: can this feature be accessed from within one's favorite open source operating system? If so, I'm guessing that it's only possible with one or two brands of winmodem, but hey, if the price is right, it might be part of a cheap solution to the submitter's problem.
  • Intercept box... (Score:4, Informative)

    by SmoothTom ( 455688 ) <> on Tuesday June 20, 2006 @03:56AM (#15567264) Homepage
    Years ago (when I still had landlines) I had a box that intercepted all incoming calls without allowing the phones to ring. It delivered a simple message "Please enter your desired extension, or, if you do not know the extension, please dial "O" or wait on the line. Bleep!"

    People were given one of several numbers to enter: 472 for family, 333 for work, 505 for businesses, for example.

    472 always rang through with a particular ring, 333 rang through with another, 505 it would allow through or not depending on how I set the switch, with yet a third ring style.

    Anyone who didn't have a good three digit number went to the answering machine, with no audible ring on any phone.

    It was simple and effective, and anyone with the proper code could get through from any touch-tone phone.

    People never had any problem with my giving them an extension number, as in "Call me when my car is ready, 206 555 0293, extension 505.)

    I don't know if anyone still makes that simple box, but it would be worth checking for...

  • No Problem (Score:5, Insightful)

    by Greyfox ( 87712 ) on Tuesday June 20, 2006 @04:08AM (#15567310) Homepage Journal
    Pick up a Digium FXO/FXS card. Technically you only need the FXO module (The bit that plugs into the landline) but unless you have a SIP phone handy you'll need something to plug a phone handset into. You could try using a software-only phone but those things seem to be a bit of a pain in the ass. If you have more than one landline you can pick up a variety of combinations, such as FXO/FXO/FXO/FXS or FXO/FXO/FXS/FXS. The card I have supports up to 4 modules and you can mix and match modules to your heart's content. Note that you'll need to plug a plug from the power supply into the card if you plan to use the FXS module. This provides ring voltage to the FXS modules.

    Slap said card into a Linux or Windows box. I chose Linux but it seems asterisk has been ported to Windows, too.

    Now grab asterisk. If you went with Linux you'll have to download and install the Zaptel drivers for the Digium card, too. I haven't had much luck with the Debian packaged Asterisk and prefer to compile it from the CVS tree. Once you've got asterisk installed you can modify your extensions.conf file. Make some local extensions (You can use your FXS phone and a SIP soft phone like Linphone to test these.) Now you can do ALL SORTS of fun stuff. My home setup has a little voice menu system that asks you if you're a telemarketer and then asks you to dial 1 or 2 for myself or my room mate. If we don't pick up, the call goes into a voice mail system very simlar to what I have at work.

    Eventually I plan to sign on with a VOIP service and keep the landline only for inbound calls and 911 service. You can also route local calls over a landline and long distance calls through a VOIP provider (or one of those 10-10 serivices if you prefer using one of those.) You can also set up speed dial keys for any combination (#1 on my phone gets you Abo's Pizza in Lafayette.)

    I suggest that you keep an actual non-wireless phone plugged into one of the other landline ports in the house -- even if you're on a UPS, a protracted power outage could end up leaving you with no way to call 911. Having an old non-wireless phone around is the safest thing to do -- they draw voltage off the phone line to work, and that usually stays up. Just make sure you don't have to plug the phone into anything other than the phone line and you'll be good to go.

    Asterisk takes a fair amount of configuring and it can be intimidating at first, but the flexibility it offers to the home user is unparalleled by anything else in its price range. For a home user, anything coming even close to it would be well out of the price range of most people.

  • I would prefer something like a small, solid-state hardware device. Is there any such thing available?"

  • I don't want my PC turned on permanently

    Well, keep in mind that this is just one application, and that there are other things that an always-on PC can do (e.g. MythTV, various "home automation" stuff, periodically record cheapo "web camera" inputs for security, serve files to your other PCs, etc). Just get ambitious, and pretty soon you'll have yourself talked into needing a PC turned on all the time. :-) Then the challenge is to build the box that can do all that, with minimal energy usage. Oooh, a ch

  • Tossable Digits provides a disposable phone number that allows YOU to control who calls and when. It's cheap and does what you want it to -- control calling. []

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