The Evolving SIP Trunk

By David Byrd

It is important to note that SIP trunks have evolved from just providing cheaper, more reliable VoIP calling. Of course, there is nothing wrong with cheaper business quality phone service; however, our industry spends so much time reminding people about the ability to save up to X percent that it tends to forget to mention the other benefits of having a SIP trunk.

SIP is first and foremost about managing sessions. For that reason, a SIP trunk innately supports business continuity through either remote call-forwarding or alternative routing when a session cannot be established. Similarly, dynamic load balancing and geographical distribution of calls can be done based upon real-time information gathered while setting up the session based upon SIP requests and SIP responses from user agents or end-points. Business continuity, dynamic load balancing, and geographical distribution of calls have been SIP trunking options for years. However, recently a couple of new capabilities have been added to the mix.

Long desired by call centers, support organizations and marketing companies, has been a burstable SIP trunk. Burstable SIP trunks allow a user to exploit more call capacity than purchased for a period of time or up to a given amount. For example, if a customer purchases a SIP trunk capable of supporting 10 simultaneous calls, then the 11^th call is either blocked (busy signal) or sent to voice mail. With a burstable SIP trunk, the 11^th call can still be delivered if there is enough bandwidth available. Obviously, there is a charge for the burstable service and a limit as to how many calls can exceed the original order.

An intelligent or featured SIP trunk offers basic phone functionality for SIP trunking customers that do not have a key system, PBX or IP PBX. BroadSoft and other hosted communications platform providers provide features that can enhance the value of a SIP trunk such as call waiting, forwarding, voice mail and more. This dramatically expands the market for a SIP trunk to include businesses without any phone system that are dependent upon the local ILEC or CLEC for actual phone features.

Finally, SIP trunks are expanding beyond unlimited long distance calling within North America. ANPI and a few other SIP trunking providers have expanded the number of countries to include some in Europe, South America and parts of Asia. While several VoIP providers have done this for residential and SOHO customers, only recently has this been offered using SIP to SMBs and enterprise customers. ANPI may be unique in offering 37 countries over a SIP trunk.

SIP trunking will take over T1s not just on price but because it offers the best path to future applications and services.

David Byrd is chief marketing officer and executive vice president of channel sales for ANPI ZONE. He previously spent five years as vice president of marketing and sales for Broadvox and before that was vice president of channels and alliances for Eftia and Telcordia.