SIP Trunk Service Licenses
SIP Trunks are in essence simply IP "trunks" using the SIP protocol. They are not trunks in the classic sense but are virtual trunks that are created and destroyed on dedicated or shared data pipes as the trunks are needed.
The key advantages to SIP Trunks are commonly the price and flexibility. The main negative is risk. In SIP Trunking scenarios, the voice traffic is commonly riding alongside data traffic. This sharing of bandwidth increases complexity and risk accordingly. Therefore, while pricing may reflect a savings in overall direct costs, some customers may not find a full SIP Trunk implementation risks to be worth such savings. In most configurations however, a combination of SIP and traditional trunking offers the best risk/reward scenario where SIP trunks can be utilized for long distance and International dialing and traditional trunks can be used for faxing, modems, 911, etc. each offers a clear advantage in their own rights in these various areas however for standard local calling the value can vary widely across markets.