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

How To Explain SIP To A Non-Technical Person

Good luck with this one, trying to explain SIP to technical people is tough enough.

Here’s some very simple short statements that may help …..

- SIP enables telephony over the internet network

- SIP allows us to packetize and prioritize voice traffic over digital circuits.

- SIP is a way voice is packed into a digital signal that is then enabled for transfer through the internet.

- SIP digs a channel in an IP network so voice/video can flow between two (or more) places. When you finish talking, SIP shuts the channel up.

- It's an internet protocol like HTTP for web browsing, only this one is used to make a phone-like connection between computers, pda, voip-phones or other devices that can talk over the internet.

- SIP is a protocol that allows unlike mediums to communicate. All you really need to know is that SIP is the new PRI and is more cost effective from a trunking perspective.

- SIP has nothing to do with the internet.... regardless of where, when, or how voice traffic is being transmitted. f it's being sent as 0's and 1's... SIP is what differentiates voice from all other data.

- SIP enables you to eliminate the cost of maintaining two networks (POTS + Ethernet) by putting your phone traffic on your Ethernet network.

- SIP is a business-class, integrated voice and data service with connectivity provided to your IP-PBX (a telephone switch that supports voice over IP)

Or … you may explain to a non-technical person by describing the SIP VoIP operation like this:

1. Callers and callees are identified by SIP addresses.

2. When making a SIP call, a caller first locates the appropriate server and then sends a SIP request. (The most common SIP operation is the invitation).

3. SIP or VoIP is a technology that allows you to make calls between devices, be it over the local network or over the Internet (Managed or un-managed). SIP is a standards based technology that behaves very much like your old telephone line but just uses the Internet as its medium.

4. Instead of directly reaching the intended callee, a SIP request may be redirected or may trigger a chain of new SIP requests by proxies.

5. Users can register their location(s) with SIP servers.

6. SIP messages can be transmitted either over TCP or UDP

7. SIP messages are text based and use the ISO 10646 character set in UTF-8 encoding.

8. Lines must be terminated with CRLF.

9. Much of the message syntax and header field are similar to HTTP.

10. Messages can be request messages or response messages.

Now you are armed with some basic background in simple (or as simple possible) terms …. to explain what SIP is and does. Should you need help of a more technical nature in deciding what SIP solution would work best for your given business application …. take advantage of the free assistance available through:

Business VoIP Solution