I am running trixbox (but soon to be freepbx) and have 3 trunks from Time Warner with unlimited long distance for $25/month each. Their trunks come in over IP through cable and are converted to copper POTS with a modem at our facility. I take the POTS in with a digium card and it all works great. Now I need to add more trunks (2 or 3) and would like to go with a sip provider and bypass Time Warner. Due to the fact that we have the three numbers in a rotary with a lead number and that lead number is all we publish I don’t think I can add to the rotary unless I use Time Warner. So I was thinking about adding the new SIP trunks for outgoing only and give those priority for outgoing. After they are full then freepbx would use Time Warner for outgoing. All the while Time Warner is handling all the incoming. I don’t know who to go to for SIP trunks. Obviously I would want cost to be below $25/month or I will go with Time Warner. Any ideas on who to go with?
Vitelity works well.
Not sure about TW but with most providers you can set a busy forward on the last number in your hunt group and forward that to another provider’s DID.
Just tried to call them and was transferred to sales. The phone rang and rang and rang till I hung up.
That will show them !! 
It is certainly hard to make sales that way. No option for voice mail or anything.
I didn’t endorse them, Cable companies use docsys not sip so anything you get from them will require a hardware interface, in my experience they are also not on your side if you try and use SIP/RTP over their network and it will seem that they penalize you if you try, perhaps because they impliment QOS/TOS in a possibly anti competative way. Not that I am saying they are not in complience with the law suits they lost . . . . .
The cable companies can be challenging although I think they have gotten better in the last year of so. It’s ironic that many of the SIP providers lack telephone skills but Vitelity’s Portal is so easy you really don’t need to speak with anyone. Your risk is 35$ and you can be up in minutes. They are certainly not perfect, and YMMV, but I’ve had good success with them when I can’t justify a PRI.
It is easy to find providers who will terminate your calls (outbound) for less than one cent a minute, (that includes most of the world apart from revenue sharing cellsystems outside the US, perhaps with a small premium for International)
If you chooose per-minute there is usually no trunk charge (or even the concept of a trunk which is generally specious for SIP.)
http://www.voip-info.org/wiki/view/VOIP+Service+Providers+Residential
or more generically
Caveate the “soft-caps” that all the “trunk” providers limit you to, as Clinton said it’s just arithmatic, as I add “Read the small print” connecting SIP calls to the PSTN costs, even for the big guys, so there is no ultimate free-ride out there. Also caveate that a vendor half a world away CANNOT provide as good quality as the one two hops away network wise, the limiting factor of VOIP will always include your “last-mile” from your ISP , some hate that you use SIP because they offer more expensive in house VOIP.