A SIP trunk is a direct connection between your organization and an Internet telephony service provider (ITSP).
It enables you to extend voice over IP (VoIP) telephony beyond your organization’s firewall without the need for an IP-PSTN gateway. This simpler configuration is easier and less expensive to design, operate, maintain, and upgrade.
In addition to VoIP calls, SIP trunks can also carry instant messages, multimedia conferences, user presence information, Enhanced 9-1-1 (E9-1-1) emergency calls, and other SIP-based, real-time communications services. Microsoft Office Communications Server 2007 R2 users can place local and long distance calls with caller ID and call hold over SIP trunks. As SIP-based communication technologies advance and SIP trunking becomes commonplace, additional services are likely to become available.
With all of the benefits that SIP trunking provides (especially the substantial cost savings), it’s no wonder that SIP trunking is a hot topic in unified communications.
Long distance service typically costs significantly less with a SIP trunk connection.
Because SIP trunks connect directly to your ITSP without traversing the publicly switched telephone network, you can get rid of IP-PSTN gateways and their attendant cost and complexity.
Deploying SIP trunking is a logical step towards the goal of having a single, IP-based network, rather than redundant telephone and data networks.
With a SIP trunk connected directly to an Internet telephony service provider, you can dispense with costly BRIs and PRIs, replacing them with service that can cost significantly less. Furthermore, with SIP trunking you don’t need to buy lines in blocks of 24 or 32. Instead, you can buy the bandwidth you need, in smaller increments, and at better prices.
With a SIP trunk in place, you can extend existing capabilities with additional services, such as E9-1-1 emergency calling. In the future, we expect ITSPs will to new services, such as greater integration with mobile phones and presence information on devices that are not running Office Communicator.
