sundance-communications.com/forum Forums General General Telephone & Systems Information SIP or old skool PRI

Let's say you have plenty of bandwidth. Built with redundancy ontop.

PBX supports SIP as well.

Would you do SIP trunks completely ?
Order a dedicated T1 and have voice ride over that as primary and then use SIP trunks as overlaps.

IME, it depends on who you speak with.
Telcom shops tend to say dedicated T1 and or muxed data circuits that have a IAD on the prem that still gives you the SIP trunks over the same provider.

Then you have the latter options, in which SIP trunking can get downright inexpensive....but then there is a certain level of QOS that kinda goes out the door.

Just curious what camp ya'll believe in.

I am in a mixed IT and telecom shop. At our office we use a dedicated T1 for our SIP trunks and a coax circuit form the cable company for our data. Our network is configured to route data over the T1 in the event of an outage on the coax circuit (which is often enough to give me ulcers at 30).

We recommend the same for our customers. We do have at least 1 customer that shares data and SIP on a fiber circuit, however. It's only been installed since November, but so far so good. In all cases, however, the SIP is provided by the circuit provider, and NOT a third party.

We will not, however, install a system for which the primary voice connection will be provided via SIP over any circuit without an SLA. Charter does not provide an SLA for its coax circuits, even for business customers, so we have exactly 0 customers with SIP over cable.

Bottom line, copper is going away. There are cheaper alternatives, but they MUST be implemented in the correct way to be as reliable as possible for our customers.

SLA mean nothing to me....all it basically states is how much money you will get in the even of X period outage.

Well, true. And there are some carriers I could definitely say that makes sense with, On the other hand, we've had far far fewer problems with circuits that do have an SLA.

Here PRI. It's still cheaper and more reliable. When you talk SIP EVERYONE provisions differently so to say there is a standard...no. We have used SIP trunking for 10 years and it just costs more here. The only reason we had it was to show proof on concept.

Our experience is that SIP is more expensive, but offers features not available with a PRI. Redundancy and disaster recovery, to be specific.

We have 400 DIDs on SIP for corporate HQ, with 46 SIP trunks. This is duplicated in our remote data center; 46 SIP trunks and redundant PBX. The remote data center is linked to HQ with two separate point-to-point fiber circuits, from different carriers.

In case of failure on the primary SIP trunks, inbound calls automatically fail over to the remote data center and redundant PBX. Using ARS, outbound calls fail over as well. Depending on the type of failure, calls can be routed back to HQ or any of our 50 plus networked PBXs in the system.

We took it one step further and protected all of our remote office POTS and PRI numbers with CLAR, with those protected numbers forwarding to another group of SIP DIDs. Using the AT&T portal, we can call forward any of the SIP DIDs anywhere we want.

Four of our remote offices were designed as disaster recovery/business continuity sites, with lots of extra data drops and electrical outlets installed in conference rooms.

During last month’s cold snap, we had a pipe burst in one of our offices. I repointed their inbound calls to one of our continuity sites, installed temporary IP phones and programmed a new auto attendant and ACD in less than four hours.

SIP is great if you’re really serious about redundancy, but you’ll definitely pay a premium. Sorry for the long post.