Wednesday, May 15, 2013

Traditional Telecom Clouds SIP’s Simplicity

With traditional offices, you have to navigate the costly and time-consuming  process of setting up 30-60 days before you can configure and use your phone system.  With SIP trunking, setting up phone service is easy and only takes 1-3 days. 

Why SIP makes sense.
With SIP, you can provision customer trunks in minutes rather than weeks.  You don’t have to deal with a local exchange telephone company, extraordinary lead times, poor customer service and lack of flexibility and responsiveness.

However, for those folks who have been in the telecom and IT sector for a long time and who are used to a traditional way of setting up phone service/system, SIP can be a scary little word. It actually seems to repulse the most established telecom aficionados. But, I assure you, SIP is MUCH easier than you think, and I will prove it.

It’s simple, it works! It saves time, money and it’s easy.  
People just starting in telecom have the home court advantage when it comes toSIP.That is because their brains haven’t been hard- wired to think in terms of traditional telecom (POTS lines/PRIs), which can be rather complex and time consuming.   So having 10 years+ experience in the telecom industry actually puts you at a disadvantage. You have to re-train the way your brain thinks when it comes to SIP. But once you do, you and your customers will be grateful. Trust me! 

Think about the steps needed to set-up a traditional land line with long distance (POTS).  
  • First, you are limited to what local providers you can use
  • And then once you determine the local provider to work with, you need to schedule installation of the local POTS line(where someone has to physically connect on-site / activate phone lines)
  • Then you must coordinate with the LEC to change the PICC to a 4 digit carrier code for thelong distance carrier, while at the same time making sure that all PICC freezes have been removed. 
  • To determine pricing, you have to incorporate line charges, usage rates, PICC, and EUCL fees.
If you can understand all of that, than you are a seasoned telecom professional and you are probably frustrated with SIP. 

Okay, let’s start with the basics. 

An IP address is the backbone of SIP. And don’t worry what the IP address technically does, just understand that it’s an address that represents you, or in this case, your phone system within the Internet.  If it’s a public IP address, it’s where you can be reached over the public Internet.  If it’s private, then it can only be reached over a private network, like MPLS or private LAN.  To setup a SIP connection between two parties, each party loads the other’s phones system’s IP address in to each other’s phone system and plugs it into their Internet connection (if public) and then, well, that’s it. To setup service with a carrier, a customer will exchange IP addresses with the carrier, plug in their Internet and test.   The SIP trunk is now born…

A SIP trunk is a virtual circuit.  What the heck is that??  Since there is no physical connection that represents the SIP trunk other than the Ethernet cord plugged into the phone system, it’s hard for us to get past the “what the heck is it” stage.   The best way to explain it is to tell you how it’s bound. Well, to compare to traditional services, standard PRIs are physical trunks made up of 23 call paths or DS0s or B channels (ugh).  Consider SIP trunks as that same type of connection made up of a preset number of call paths that you can make calls out and receive calls via DIDs.  The difference is that SIP trunks can allow thousands or tens of thousands of calls simultaneously.   What binds a SIP trunk is not the physical nature like that which limits PRIs, but instead is bound by Internet availability, phone system capacity, and carrier set predetermined limits.   Since each active call sucks up Internet (40-80 KBPS per active call), you can only have as many calls active as you have bandwidth available.  Your phone system also may have limits for various reasons that would only allow a certain amount of active calls. But the most important defining characteristic of a SIP trunk is the preset number of call paths the carrier assigns to the trunk group.  If a carrier only allows for 10 concurrent calls, the 11th simultaneous call is going to fail.

What is needed to make SIP trunking work?  You need a SIP compatible phone system, or a gateway that converts SIP into traditional services, bandwidth and a proven carrier?

If you have any questions or would like to learn more, please contact me, Max, at

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