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SIP Trunk instead of PRI's

I work in a rather large organization that has several thousand phones. We currently have approximately 10 PRI's from one provider that we use for inbound outbound dialing.

We are discussing possibly trying to move to use SIP service provider. However I have a couple of questions that I can't seem to find an answer for.

1. How do I find a SIP service Provider?

2. Would the SIP service provider usually bring in a dedicated line to the organization such as a DS3 and connect this to there network?

3. How do I calculate the amount of bandwith that I need.

Thanks for any help

Hall of Fame Super Gold

Re: SIP Trunk instead of PRI's

1. good question, can we skip to next ?

2. a pure itsp, no. someone that is both an isp and a tsp, yes. expect cost to be hefty for a ds3 worth of voice. nowadays, even traditional carriers offer sip service.

3. a g711 call takes about 90 kbps, multiply by the maximum number of calls you want be able to take. In the future, when the better codecs will be universally available, this figure can be reduced by four, but as of today, g711u is only practical choice for toll quality voice.