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More than 200 companies in the U.S. offer Session Initiation Protocol (SIP) trunking in one form or another, giving rise to the question of which provider is best for a given organization.

Increasing numbers of unified communications (UC) and legacy private branch exchange (PBX) companies are employing SIP. And due to its efficiency and flexibility, SIP is likely to become the access standard for the foreseeable future.

Rather than getting overwhelmed by the myriad service offerings from various providers, an organization transitioning to SIP should consider key criteria covering a smaller aggregate of vital functions. Considering existing and future requirements will also facilitate a solution that integrates easily and circumvents long-term contractual difficulties.

The Case For SIP Peering

In many ways, direct SIP connectivity effectively renders the public switched telephone network (PSTN) obsolete. Compared to PSTN, SIP is a more straightforward solution. It doesn’t require G.711 transcoding to and from the PSTN, which necessitates the use of jitter buffers and gives rise to delay. Unlike PSTN, SIP also supports wideband speech codecs which offer far better voice quality. Wideband represents the proverbial “next generation” of services since it facilitates the deployment of other utilities within the signal.

Enhanced Efficiency and Practices

SIP peering employs sets of protocols that enhance the potentials of the interconnection, represented as capabilities that reside within the SIP proxies themselves:

  • Transparent local area network (LAN) services (TLS) and SIP identity are used to reinforce security.
  • Monitoring of inter-provider communications facilitates ease of accounting and invoice reconciliation.
  • Location of terminating providers through carrier telephone number mapping (ENUM).

“Interviewing” the Potential Provider

Knowledge of how a potential SIP provider’s network is run and architected is essential to crafting the appropriate solution. Asking questions about implementation, operational models, and call quality and availability will aid in this pursuit. A good indicator of how well a provider’s SIP is architected is their peering with IP and SIP networks. How well the service provider executes this will determine the quality of the interface between other IP providers and the Internet at large.

It is important to know how wide a range of IP peering points the provider uses, where they’re focused, and if their interface with regional providers employs the proper local POP connections. Proximity affects voice quality, so it is prudent to inquire on the distance between IP peer points and customer locations.

Since interconnecting provider networks is integral to the protocol, SIP peering doesn’t require new extensions to SIP. It was designed to operate across platforms with divergent extensions and capabilities and possesses integrated negotiation capabilities that proscribe contingencies to baseline parameters if it encounters incompatibility on one end.

It’s critical that the support capabilities and competence of the provider’s team will serve the organization’s needs. This is the final and perhaps most important consideration in choosing your SIP peering provider.