What Is SIP?

In the digital age, SIP is analogous to the the dial, ringer and hookswitch on a conventional landline (POTS-Plain Old Telephone Service) telephone. Where the POTS telephone made use of the analog domain (DC voltages and currents, audible tones and large AC ringing voltages) for signaling and supervision, using rotary dialing or touch-tones for telling the telco where to route your call, the hookswitch for initiating/answering/terminating the call, and the ringer for alerting you to an incoming call, SIP uses specialized messages sent over packet networks to do the routing, signaling and supervision over digital networks.

Old style telephony depends on analog (continuously varying) voice signals between the customer premise and the telephone company central office, while modern SIP telephony digitizes voice signals (discrete 1 & 0 voltage levels) at the source, and transmits them over packet networks. The digitized Voice is sent over the Packet Network using Internet Protocol, much the same as data, hence the familiar acronym VoIP, Voice over Internet Protocol.

Note that VoIP and SIP can be used together, but there are other signaling methods aside from SIP. Skype, for example, uses a proprietary messaging protocol , whereas SIP is more of a near-universal standard. Hence, SIP networks tend to interoperate well, while it's difficult to make a VoIP call between SIP and Skype without traversing a specialized gateway.

SIP is one of several VoIP protocols like Megaco H.248, MGCP, RVP over IP, SAPv2, SDP, SGCP and Skinny.

To put it in very basic terms …….

SIP says it all. Just picture (pitcher ;-) a glass of water.

It's not the glass (network) nor the water (the communication itself).

SIP is the straw, the signalling channel which sends the water to the right location (your mouth).

Should you need help in deciding what SIP solution would work best for your given business application …. take advantage of the free assistance available through:

Business VoIP Solution