atcomsystems.ca/forum Forums TDM Business Telephone Systems Inter-Tel Telephones & Systems SIP trunking

Has anyone used SIP trunking? How is the reliability and quality?

Works fine, sounds fine, as reliable as your circuit carrier. Know what you're getting into and if SIP trunks are the 'right' solution.

I'm sticking my toe in the water. We're opening a branch in the UK and thinking of using them as a guinea pig. Define the "right" solution for me.

We have five T1s in our main location. The idea of saving $60K+ a year is awfully inviting. We have a 20M pipe

About time I get back to you on this...

The "right" solution means you can benefit from it. In the case of SIP trunks, they really shine in configurations where you have a distributed business operating in multiple rate centers (area codes) and want all of them to share a common set of trunks without issue. You can port numbers from any area code to the SIP trunks and they appear in one PBX. Plus you can order them in any quantity needed so if you need more than a PRI but not two, you can order what you need. I just installed 30 SIP trunks on a Mitel 3300 for a 13 site company with around 125 phones. They run the whole place off those lines and eliminated local trunks at the remote sites as well as ditched the aging local key systems at each site. Imagine not having to pay maintenance for 12 out of 13 systems!

Of course you could have done a similar config with a few PRI's and it would work, but you'd have to forward the remote pilots to a DID in another state, pay that LD and still have to carry that trunk as a recurring debt in addition to any rate center violation fees.

I'm not in Sales so I'll leave the smoke blowing to that group. Do your homework, don't guess and don't half-ass a SIP project. Your Internet circuit dictates how many you can support

That's a great scenario. I don't know that it fits our infrastructure. We're located in Kansas, with an office in Canada and another going in the UK. All IT functions are located in KS. The other two offices receive data via an AVPN and the use of Citrix. Which is great for data. Phones? Not so much. All of the branch office internet traffic is funneled through KS. So imagine making UK local calls from Kansas. We could get a second internet connection for the UK office dedicated to the phones. What bandwidth would you suggest? A business class DSL would have plenty of bandwidth, but would it be reliable?

Each SIP trunk provider will tell you something different. I would follow their suggestion so if issues arise you have that point covered. Most of them will use G.711, so you could calculate by multiplying the G.711 codec by the number of concurrent calls desired. We just did 30 trunks on a 3.0M DIA. Works great.