Just wanted to mention a few VoIP providers that I use on my home Asterisk system.

• VoiceStick / i2telecom – Using their Next2Nothing plan (pay-as-you-go) I have a DID number local to my parents. They dial a local number and I pay 1.2 cents per minute plus a couple dollars a month for “911 recovery fee” (for an incoming-only phone number!). Audio quality has been excellent. If it weren’t, my family members would surely tell me so.
• FWD – every homebrew VoIP system should connect with FWD. Why? Well, because it’s free! I am connecting using both SIP and IAX2. I use it only to connect to toll-free numbers and to test connectivity using some of its test numbers.
• Gizmo Project – here’s a clever way to get a free DID number thanks to Gizmo Project and Google’s Grand Central. Sign up for a free Gizmo account, set it up in Asterisk and make sure it works. Then sign up for Grand Central. (Need an account? Leave a comment and I’ll send you an invitation.) You can point your Grand Central number to your Gizmo account. Result: People call your Grand Central number (a regular phone number) and your VoIP system receives it.

  Cool, until you decide it’s annoying to respond to Grand Central’s “Press 1 to accept the call…” menu every time your phone rings. Instead, make Asterisk “press 1” for you when a call comes in and before delivering the call to your phone.

  Put a custom context in Gizmo’s peer definition, like this:

  context=custom-gizmo-in

  Then create that custom context in extensions_custom.conf (for FreePBX) or directly in extensions.conf if you’re hand-editing plain Asterisk:

  [custom-gizmo-in] exten => s,1,Answer exten => s,2,Wait(1) exten => s,3,SendDTMF(1) exten => s,4,Goto(from-pstn,s,1)

  (The goto in step 4 sends the call to the generic “incoming” context after the DTMF “1”; modify as necessary.)

• ??? – I use a cheap termination service (outbound calling) whose terms of service state that “All customers … are specifically prohibited from disclosing to others that they use [the provider’s] service.” I leave it as a mystery for the reader. (However, I’m pretty sure I heard of this provider by word-of-mouth — contract-breacher!)
• CallCentric – This one is on my radar. I am signed up for their free service and a single “Cheap DID” to test things out. So far I have been very impressed with their customer service (answering a non-trouble question ticket within two hours), the sound quality, pricing, and availability of DID numbers. It seems like they offer DIDs everywhere and can port (LNP) just about any number. I may port my listed home phone number (currently not connected to my VoIP setup) to this carrier.

No mention of the big guys: Vonage, Packet8, or AT&T or Verizon’s VoIP service, for three reasons. One, most don’t allow you to connect to them using a PBX (Asterisk). Two, they’re expensive. And three, if you’re home-brewing VoIP, you are probably a geek or trying to “stick it to the man.” I realize that some of the carriers that look like “little guys” really have big guys behind them, but many of them don’t. They’re just trying to make a little money reselling service from wholesale carriers and adding their own little features to make telephony a little cooler or more fun.