Heh, I used to do multi-conference room / theater AV integration for large defense companies. The number 1 problem was always audio.
1. Test. Test test test. You can get almost any cheap thing working well if you bother to test and tune everything BEFORE the meeting. The most expensive thing can fail for silly reasons if you don't bother to test everything BEFORE the meeting (usually because some executive schlupp dials into both the audio bridge and VTC MCU at the last minute). Then freeze the configuration. Yeah, good luck freezing the configuration with engineers and tinkerers running around.
2. POTS sucks. Maybe some telephony devices are able to negotiate better than 8kHz 8-bit audio sampling if their codecs match up, but you're better off going with something with VTC-quality audio using H323. Most VoIP teleconferencing lines don't bother trying to beat POTS audio quality. So even if you have a nice Polycom phone that does good AEC and NC, you're still going to strain to hear what's going on.
3. Speakerphones suck. Most of them don't bother doing good AEC and NC. Get a good bluetooth or USB headset. Gaming teamspeak headsets are relatively cheap. As long as it's digital, so they don't introduce any analog amp noise from the system.
4. PC/laptop microphones suck. I don't know why no one bothers to test them to the same level as your average cheap dumbphone speakerphone. They pick up all kinds of system electrical noise, and rely on software to do any AEC or NC, which adds more latency. About a quarter of the people in our daily standup have laptop microphone fails on Google Hangouts or Skype each day. Most end up dialing back in from their smartphone when that happens.
Anyway, all that said, our current standup room setup consists of a Google Hangouts room on a permanently-fixed Mac mini with a $50 "Blue Snowball USB Condenser Microphone" and Logitech USB camera attached to it (the USB audio coming in from the Logitech camera was deemed insufficient, even for the small room we had it in.). For remote participants, I've had good experiences with extended use of the $200+ Jabra PRO 9470 Mono Wireless Headset, which is switchable between PC and POTS/VoIP phone use, but a simpler/cheaper bluetooth headset would probably work just as well paired with smartphone/PC.
And set up an echo server for everyone to test their setups. https://support.google.com/cha... . Or at least go to http://www.onlinemictest.com/ or something. Did I mention you should test?
I'm also looking forward to someday playing with Amazon's Echo thingy someday, since for $200 it seems to have a lot of the technical audio features of more expensive audio conferencing systems:
assuming it will be able to act as a simple bluetooth speakerphone instead of only for all of the other AI junk they're cramming into it.