I signed up with Callcentric -
They have unlimited outbound for 19.99/mo
If you don't need unlimited -
500 min plan for 6.95/mo - or -
1000 min for 12.95/mo
Inbound is separate cost - (however right now) they are offering free NY state numbers for incoming
The plan I have included ~20 extensions - i.e. can register on any combination of IP phone/Allstar box/mobile device - supports I believe 3 simultaneous calls total? - I have not put this to the test though... Only ever tried 2 at a time... works great, if you have a voip provider at home or wanted one. Really inexpensive to do both.
I have literally been on a call for 3+ hours from home, and it's been solid.
Easy to setup in Asterisk - for outbound - have not setup inbound though, im sure you could.
You can dial one extension from another easily - so you can call home to your voip phone with a 3 digit ext.
I'm using a polycom phone (voip) with the service, and over the last ~month has been great, no issues I can find...
Also unlike some providers - also includes 911 access - which can be beneficial!
73's
Mark KC7DMF