My VoIP trunk of choice (after admittedly trying few others) is FlowRoute. They have a number of advantages over pretty much everything else:
- Cost of minutes: Basically $0.01/minute in or out within the US. A little more to accept Toll-free calls.
- Cost of DIDs: Basically $1.25/month + activation.
- Ability to purchase DID blocks (a range of numbers) for cheap (even though those blocks might put your business somewhere north of eastern Sasquatch-uan).
- Ability to tell you EXACTLY how much money you have left…down to the 1/1,000,000th of a cent. As of this writing I have $25.92119295 of credit.
- Pay as you go, with automatic top-off available.
- E911
- Caller ID CNAM pushing (after approval of CNAM)
I have heard their support is not stellar, but they don’t do that much to warrant you wanting support.
They provide very straight-forward instructions for configuring sip trunks within FreePBX or Asterisk. Overall, not much to dislike about this company or the service they provide.
You can also read my full VoIP tutorial.