[asterisk-users] Enterprise quality SIP provider

[Vikas]

I need to setup incoming (over an 800 number and some local DID's) and
outgoing phone calls (all over the country) with an Asterisk server.
This asterisk server has 20 Polycom 430 phones connecting to it.

I need the best possible SIP provider out there. I have tried
http://www.nufone.net and http://www.broadvoice.com and they do not
even come close to the expected quality.

Does AT&T allow companies to connect to their backbone network using SIP ?

Any suggestion of companies which provide enterprise quality SIP
termination and origination.

The office is in a building which has a data center in the basement
and has DS3 coming into the data center. I can buy as much bandwidth
as I want from the data center.

Regards,
-- 
Vikas
http://www.stanford.edu/~vikask/