We're looking for an ISP with SIP trunking and DIDs to host our FS servers, and are having a hard time locating an ISP who meet these two requirements
a) can handle 10,000+ simultaneous inbound ports 
b) returns our calls in timely manner

We have a six-figure annual budget for this service ... and so far the "big guys" sales teams can't get it together to put together a bid.

The ideal partner would share with us the backend telcom revenue in the neighborhood of .5c/min, but we're open to other arrangements.

Does anyone have any recommendations for ISPs with SIP trunking and DIDs that they can share?  Specific salespeople contact info especially appreciated!

Thanks,

Dale