SIP Forking: How it Works?

SIP (Session Initiation Protocol) is a communication protocol that is employed in signaling and managing multimedia communication sessions. It is used over Internet protocol (IP) networks to provide a huge array of services like voice calls, video calls and instant messaging.

The main reason why SIP is preferred is that it is a highly flexible protocol with a huge depth. Due to its design, it is able to act in a general purpose manner in order to establish real-time multimedia sessions between groups of participants. In simpler terms, SIP is able to set up audio and video multicast meetings along with the old school telephone calls. One of the most important features SIP provides is forking, which allows distribution of calls to the various extension.

The Basics

SIP forking can be defined as the process of splitting a single SIP call to multiple SIP endpoints. In the traditional models, forking has to be initiated manually. Moreover, regular minute charges or in some cases double minute charges can be applied. With SIP forking several phones can ring at once or a set of phones can ring in a sequential order until they reach the end and are sent to the voice mailbox.

The term “Forking” means dividing a direction. The applications which are installed on SIP endpoints are termed as “User Agents”. These end points or user agents can work in two manners: They can either be a user agent client (if sending a request) or a user agent server (if receiving a request). When a request is sent, a session is initiated; the phone looks for the best available user agent by using a separate program which is called a “Back-to-Back Agent” whose job is to connect the server and client user agents.

Call Rules in SIP Forking

When using SIP there is an option of setting up a set of pre-determined rules called Call Rules. These call rules enable a SIP network to automate basic tasks for an efficient workflow.  Call rules are of two types- Dynamic and Manual.

Manual rules are simple. They check for a condition and then either perform or avoid a certain action. For example, you can set up a rule that makes sure that your phone does not rings at all when anyone calls, the caller is directly sent to the mail box. A modification to this rule can be the addition of a few VIP callers that are allowed to call you while others are sent to voice mail.

Dynamic rules are a bit more complex. Citing the same example, a dynamic rule will automatically check your calendar and the time of the day to know when is the time you might be in a meeting or otherwise unavailable and it sends the caller to voice mail automatically. You don’t have to prompt it to do anything.

These call rules make the automation of telephone based work centers easy, allowing for a lot more productivity.

In a Nutshell

Any VoIP service provider worth its salt uses SIP for providing the best communication to its clients. While there are other alternatives like H.323, SIP provides more features with a less complex architecture thus making it the clear winner against other protocols of a similar nature.

There are many advantages that SIP provides for VoIP communication which includes:

• User Location and Registration
• User Availability
• User Capability
• Session Setup
• Session Management

SIP has allowed VoIP to reach its current success. It has shattered geographic barriers and made the whole world a single workplace. With the wonders of SIP forking it has helped businesses increase their productivity and grow productively.