Will Rickards said:
Oh and what do you do about having multiple phones in the house?
And are there upstream bandwidth requirements?
There's two options. One, you can just plug say a cordless phone system into the TA, and leave the home wiring alone. Other option is to disconnect the outside copper line from your phone junction box, and then connect one of your phone sockets into the TA. That way, all your phone connectors are hooked up to the TA, and work like normal.
You can also get a second VoIP line if you want, the TA has two line capability,
Bandwidth requirements, they recommend minimum 90kb up/down.
The TA does monitor quality and set QoS, you can give it more priority if you wish. The TA can be placed either before or after a router, if you use one.
Caveats: it's no good if you have a home alarm system hooked up to the phone system. Also it won't work when the power is out (no residual power like a landline - I can't figure out if this is negated by having it hooked to a UPS). And 911 calls are routed based on the service address on record, so make sure you update if you move address.
Pluses: Got a vacation home? Take your TA and your number moves with you
The most popular services are:
ATT CallVantage:
https://www.callvantage.att.com/
Vonage:
http://www.vonage.com/
Vonage is $24.95 per month, but they couldn't transfer my number for some reason.
From what I've read online people seem to have call quality issues with packet8.
Unlimited US/Canada. Both have cheaper plans with minute/area limits if you're not a big caller.