Tag Archives: sip trunks

SIP Trunks, In General.

Session Initiation Protocol

Everybody is banking on this.  I certainly understand why!

Called SIP for short.  I’m going to get too much into what SIP really is and means in this write up, maybe another, but when it comes to delivering voice services to your office and business via SIP, we call that a SIP TRUNK (opposed to a copper trunk, which what you are used to)

In a nutshell, it’s a way for voice and data vendors to deliver your voice traffic to your office using an Internet protocol.  This Internet protocol travels to your office over the vast computer networks setup from the providers equipment to each AT&T hub, then to a T-1 copper trunk and straight into your office.

Now, most people do not have a phone system that can decode a SIP signal.  They just simply don’t exist (well a little, and more are on the way).  To that end, providers (such as Logix) have been forced to purchase, install and provide to you a device, usually Cisco, called an IAD.  IAD stands for Integrated Access Device.  They cost the PROVIDER generally upwards of $800 (they don’t like that, so they love this SIP trunking directly to your phone system idea, anyhow..)

This IAD will take their raw SIP “trunk” and the decode it.  On the other side of the IAD will pop network Internet access (just like from the DSL modem) along with “emulated” analog phone lines.  This box will provide a signal that is simply put, exactly like an analog, copper phone line.

Your legacy phone system knows no different.  As far as it is concerned, it’s getting a normal phone line tied up to it and that makes it very happy.

Well, with the advent of VoiP Hybrid phone systems, such as the BCM50 from Nortel Networks or the Office IP 500 from Avaya, connecting two phone systems together over the Internet or a WAN has  been a reality … using a …. you guessed it, a SIP TRUNK.

Let’s understand that the word SIP TRUNK is a general term, like the word CAR.  A car is generally used for driving.  Some people drive them to work, some people drive them backwards in smash em derbies.  Either way, they push the pedal and car goes vrmm.

A SIP TRUNK is similar.  It’s using the Internet to carry your voice from one spot to another.  Several scenarios exist.

1) System to system, handy unified communications!!

2) System to remote phones

3) ahhh, you guessed it..  voice provider to customers system… hmmm what a great idea.  believe it or not, it’s barely even possible!!

So to that end, SIP trunking is not just a replacement for traditional voice services.  It didn’t even start that way.  It will end up there though.

SIP Trunking requires very very efficient bandwidth at the customer premise. To effectively employ SIP trunking having an efficient MPLS helps too.

Now, as to a phone system that will accept a direct SIP trunk directly.  Only a few premise based, customer owned IP PBX’s exist that will do it.  Drum roll please.

Avaya (IP Office)
Nortel Networks (BCM)

As to service providers.  Here in Houston, the only one I know of is Broadvox, call me and I will hook you up with a rep, 281-894-6606

Soon to roll out the same service is Logix.  I’m sure others will follow.  Quality of service are some tough issues for a providers to work through.  Any customer at this point attempting to do a provider based SIP trunk to a premise based IP PBX is a Guinea pig, but that’s ok.

For the rest of the world, or business customers in Alabama, Arkansas, Florida, Georgia, Illinois, Indiana, Kansas, Kentucky, Louisiana, Mississippi, Missouri, North Carolina, Ohio, Oklahoma, South Carolina and Tennessee, Nuvox has rolled out their SIP trunk service.  You might want check them out if you live in those states.

Jay Harper

As always, feel free to call me at 281-894-6606
or visit us online at