Session Initiation Protocol, or SIP, is the protocol (computer language) that makes it possible for two or more parties to connect peer-to-peer, rather than through a centralized trunk. SIP can do many things, and one of them is called “SIP Forking.” SIP forking is the process of splitting a single SIP call to multiple SIP termination points. Traditional call forwarding must be activated manually. On top of that, regular minute charges, or even double minute charges may apply. Not so with SIP. SIP does forking natively With SIP Forking, several phones ring at once, called “parallel forking,” or, phones ring in a set order until they are sent to the voice mail box, called “sequential forking.”

The term “forking” comes from a computer term that means to copy or clone a direction. Applications installed on SIP endpoints are called “User Agents.” User agents can be in a smartphone/tablet, an IP phone, in your PC/laptop (softphone), or an ATA gateway. The same user agent can be a “User Agent Server” when it is receiving a request, or a “User Agent Client” when it is sending a request. This is because SIP is peer-to-peer and flexible. When the request is sent out—usually by dialing a phone number, but there also alternatives—instead of dialing a number, what you are doing is initiating a session. Once that session is initiated, the phone seeks out the best available user agent using another program called a “back-to-back user agent,” which connects the user agent server and the user agent client. As part of the protocol, SIP natively looks for multiple endpoints.

SIP forking allows for call rules rather than simple call forwarding. The call rules, once set, can be activated manually, or through the magic of UCC. An instance of a manual rule change activation is hitting the “do not disturb” button on your IP phone. Your phone automatically goes to voice mail. You can set a rule that certain VIP callers still get through. You can also set dynamic rules, so, for example, your phone will check your calendar to see if you are in a meeting before it even rings.

With SIP forking, you can have your desk phone, your mobile phone, and your receptionist’s phone at the same time. But, that is just the beginning. Let’s say you have a call center. You set a call rule that every phone that isn’t busy will ring, and whoever picks up the phone first talks to the customer. We can expand it even further. Instead of one office, you have dozen employees working from home, some in different states. Using IP and softphones, the inbound call is routed to whoever can take the call.

SIP is a powerful tool. SIP empowers businesses to break down geographic barriers and improve productivity. SIP also enables residential subscribers to get great features, such as receiving e-faxes, setting call ring rules based on time of day and incoming number, and making free international calls. SIP forking is just one of the many features you can only get with Voice over Internet Protocol.