Session Initiation Protocol (SIP), is an application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants. These sessions include Internet telephone calls, multimedia distribution, and multimedia conferences. SIP invitations used to create sessions carry session descriptions that allow participants to agree on a set of compatible media types. SIP makes use of elements called proxy servers to help route requests to the user’s current location, authenticate and authorize users for services, implement provider call-routing policies, and provide features to users.
SIP is now the standard for VoIP services. Many businesses are now replacing outdated Phone circuits with SIP, lured by the range of benefits the new technology offers. Legacy phone lines sets up a circuit switched connection to allow voice data to be transmitted between callers. SIP uses the Internet and allows large phone networks to be established using an Internet connection. This reduces the amount of infrastructure that businesses need to invest in or rent. SIP systems are flexible so any number of channels can be added to accommodate business growth. Traditional phone systems come in set number of channels, imposing a significant expense on companies as they expand. In addition, SIP facilitates cheaper VoIP calls than traditional phone lines do. In the plain old telephone service/public switched telephone network (POTS/PSTN) way of doing telephony, you get additional lines as you need to increase your capacity. In the VoIP way, you can upgrade your bandwidth on your dedicated line to increase capacity. There are several disadvantages for companies that use POTS/PSTN rather than VoIP telephony. POTS-related lines are leased from a carrier. Just leasing a single line incurs added expenses. For example: Each line usually has a nominal startup charge, Each line has a monthly recurring access charge, for each POTS line, the company must pay monthly recurring usage charges. All recurring charges are based on a rate per minute per line. When you add up all the minutes from every line in operation at each of your company’s locations, the monthly costs can soar.
Session Initiation Protocol is a system that was created to launch and end VoIP calls. A SIP trunk is an online system for linking a business’ IP-based PBX to an Internet phone service company such as VoIPInvite. Rather than terminating the trunk at the IP-PBX, companies terminate the trunk at a SIP-capable session border control system, which offers extra security. By simplifying voice hardware, a SIP trunk can support a business’ telephone and multimedia requirements over the Internet and eliminate the need for costly and cumbersome legacy hardware. Analysts say that companies that embrace SIP trunking can save up to 60% on their current traditional telephony trunking costs.