And why can you not list with BT what your DID's can be, and what your internal numbers are? So when your DID is linked to crank calls, they can shut you down or notify you? In fact, the link is ALREADY there. BT know exactly what number you're claiming to be when you ring out, and which one you actually rang from.
But why should I have to deal with people able to fake YOUR DID (and thus your company's reputation) or a random or invalid DID, without any traceability?
Why should I only have that DID number as the ID I can block on? Why should someone be able to send me text from a number that doesn't exist? Or even, in some cases, from a NAME that doesn't exist (and which, thus, you cannot respond to or block), as I've seen on UK mobile phone networks?
I run a school telephony network, I understand DID usage. What I don't get is why that's not restricted (i.e. CANNOT BE FAKED), so that only YOUR numbers can advertise your DID. Wouldn't this stop me making crank calls to your customers and claiming to come from your 0800 number? Because there is ZERO protection for that at the moment, and never has been.
And that's all moot if you can't block that number. Number blocking has always been a pay-for service with BT historically, unless you wanted to block all numbers (then why have a phone?). It wasn't cheap either.
And try and report a crank call. Unless it's criminal, BT will NOT go through their records and find the originating lines. They will ask to intercept your line and see if they can't capture a repeat call live, rather than look in their history. Only when the police are involved will they discover the ACTUAL source of messages or phone calls. The user is helpless here.
(P.S. I once had a bank send 400 fax calls an hour to my parent's residential phone - that had no fax. We reported it to BT. There was no CallerID. Now they KNOW who sent those calls. They have records they could investigate, but they WILL NOT. Until you make a criminal complaint. What they did was - when we could finally get through to them - intercept the line for over an hour, meaning we were without service, and waited for the next fax - but by this time they'd died down.
It turned out to be a bank internal system on auto-send without retry-protection with a mistyped phone number. But it took DAYS to resolve. DAYS of the phone ringing uncontrollably throughout working hours all day long. You can say "You could have put a fax machine on it", but this was my parent's line, we had no fax machine, and this is BT's job to do something about. They couldn't because they do not access originator information, the CallerID was withheld, and they cannot block a number without it, unless there's a criminal complaint. And this wasn't last century.)
DID spoofing is fine. My employer does it. But there's NOTHING to say who can or can't spoof, or what they can spoof, or anything protecting users from malicious spoofing.
I should not be able to get a text message from "801" or "Insurance" (literally, not a contact name, but the originating name of the text), or a phone call from a number that I've blocked (even if they later try to call with number withheld, so employee at company who gets pissed off and wants to spam me can't just use the same line after dialling the number to withhold the CallerID), or a phone call from several thousand spoofed or unregistered numbers over extended periods of time (this should trigger so many alerts, that BT just shut the line down like an ISP would shut down an email spammer).
None of what I'm suggesting stops your employer advertising their main switchboard number for all outgoing calls.