[This is pre-release documentation and subject to change in future releases. This topic's current status is: Milestone-Ready]

Topic Last Modified: 2010-03-09

Deploying SIP trunking can be a big step toward simplifying your organization’s telecommunications and preparing for the latest real-time communications enhancements.

SIP Trunking in Communications Server 2010

The Communications Server 2010 SIP trunking capabilities enable the following scenarios:

  • An enterprise user inside or outside the corporate firewall can make a local or long-distance call specified by an E.164-compliant number that is terminated on the PSTN as a service of the corresponding service provider.

  • Any PSTN subscriber can contact an enterprise user inside or outside the corporate firewall by dialing a Direct Inward Dialing number associated with that enterprise user.

Cost Savings

The cost savings associated with SIP trunking can be substantial:

  • Long distance calls typically cost much less through a SIP trunk.

  • Expensive redundant networking can be eliminated if you adopt a single, IP-based telephone and data network.

  • Basic Rate Interface (BRI) and Primary Rate Interface (PRI) fees can be eliminated if you connect a SIP trunk directly to your ITSP at significantly lower cost. In legacy TDM trunking, service providers charge for calls by the minute. The cost of SIP trunking is based on bandwidth usage, which you can buy in smaller, more economical increments.

SIP Trunking as an Alternative to an IP-PSTN Gateway or IP-PBX

Because SIP trunks connect directly to your service provider without traversing the PSTN, you can eliminate your IP-PSTN gateways and their attendant cost and complexity. Some ITSPs offer to host a PBX for you if you choose. This can lead to substantial cost savings through reduced maintenance and administration.

If you have an IP-PBX that is nearing end of life, rather than invest in an upgrade, consider replacing it with a SIP trunk at a much lower cost.

Expanded VoIP Services

Voice features are often the primary motivation for deploying SIP trunking, but voice support alone is just the first step. With SIP trunking, you can extend VoIP capabilities and enable Communications Server 2010 to deliver a richer set of services than you can get with legacy technology. For example, the same SIP trunk that delivers your telephone service and other VoIP communications services can now provide:

  • Enhanced presence detection for devices that are not running Office Communicator provides better integration with mobile phones, allowing you to see when a user is on a cell phone call.

  • E-911 emergency calling enables the authorities who answer 911 calls to determine the caller’s location based on their telephone number.

  • GPS locations can be integrated with your Location Information server to track mobile user location.