Session Initiation Protocol (SIP) is a communications protocol used for communicating between different devices on a company network, whether on the LAN, the WAN, or across the Internet. An example of this could be a simple two-way phone conversation, using voice over IP (VoIP) on the LAN or WAN or a SIP trunk across the Internet to a service provider. A SIP trunk provides a new way of connecting to a service provider for incoming and outgoing calls; it is a connection over the Internet instead of a traditional telephone connection such as ISDN. In effect, the Internet replaces the conventional telephone trunk, allowing an enterprise to communicate with fixed and mobile telephone subscribers worldwide. (SIP is an IETF standard for initiating interactive multimedia user sessions; a trunk is a line or link that can carry many signals at once, connecting major switching centers or nodes in a communications system.)
In order to take advantage of SIP trunking, an enterprise must have a PBX that connects to all internal end users, an Internet telephony service provider (ITSP) and a gateway that serves as the interface between the PBX and the ITSP. One of the most significant advantages of SIP trunking is its ability to combine data, voice and video in a single line, eliminating the need for separate physical media for each mode. The result is reduced overall cost and enhanced reliability for multimedia services. With SIP trunking, subscribers can:
· Initiate and receive local calls
· Initiate and receive long-distance calls
· Make emergency calls (911)
· Access directory assistance
· Use fixed and mobile telephone sets
· Employ e-mail and texting
· Browse the World Wide Web.
Some of the Benefits of SIP Trunking include:
Better Prices: since a single connection is used both for voice a data traffic. SIP trunks also eliminate the need for local public switched telephone network (PSTN) gateways and costly ISDN BRIs (Basic Rate Interfaces) or PRIs (Primary Rate Interfaces). Costs can be reduced n many cases by 40 percent or more.
Efficiency. It works bandwidth dynamically between voice and data according to what might be needed.
Easily allows growth: The business can increase call capability with additional SIP trunks. Within minutes you can add however many lines you need. Adding a line to a traditional phone system can take several weeks and might even require the purchase of additional software.
Simplicity: One bill, one provider for all communication needs.
Geographic Independence: Being able to get an area code that appears local, but be located any other part of the country.
Basically, SIP trunking extends the notion of seamless connectivity within a business to customers, remote employees, anyone working outside the corporate network. SIP is in fact the next evolution of telecommunications.