ShoreTel SIP Trunk Configuration Parameters for Level 3
August 26th, 2009
Generally, we do not fill out forms given to us by Carriers.   Most Carrier forms use nomenclature that is "Marketing Speak" and not technically driven.   It seems we have 100 different ways to refer to a TDM with PRI signaling and only one of them means anything to an engineer.   There are a variety of new delivery methods being offered to clients for PRI service and it is important to understand exactly what type of circuit you are actually being given.    A PRI may in fact be a SIP trunk from a Softswitch, through a CISCO IAD with a TDM interface for your SGT1.   Not necessarily a bad thing (though you should expect problems with Fax service) but it is a hybrid circuit and not a traditional TDM T1 to a circuit switched central office.   We are always eager to assist the client by speaking with the carrier and having a dialog as to the exact nature of the circuit, but we steer clear of filling out the forms they expect their new customers to complete! Recently, while planning the implementation of a ShoreTel IPBX with 230 SIP trunks, I  had the experience of pulling together answers to L3 request for configuration data.  With the help of  Rod Davis, Juan Rubio and Steve Weinstock we were able to respond.   To my surprise, this time there was not a single marketing expression in the document!   The questions were specifically engineering oriented and designed to understand the capabilities of the IPBX that the SIP trunk service was being ordered to support.    I though it would be interesting to share that information with our readers.  The IPBX is the ShoreTel and the assumption made in these answers is that the ShoreTel is being front-ended by an Ingate Separator.   Here are the SIP configuration questions and answers: