SIP Trunking - What is it?

SIP Trunking or Session Initiation Protocol Trunking is a service connection that is mainly given by certain Internet Service Providers (ISP) or Internet Telephony Service Providers (ITSP).

The concept for this connection is to attach the telephone system of a certain company to its Private Branch Exchange (PBX) using internet servers, which then allows Voice Over Internet Protocol (VoIP).

For example, one employee of a SIP provided company calls a regular phone number. This regular phone number is called a PSTN number or Public Switched Telephone Network number. The SIP Trunking service will modify the IP of the caller to a PSTN number close to the callee. This way, it will appear as if the employee is just calling from a neighboring house or village.

This will then provide swift communication services and will lessen possible long distance charges for the company. This system can also work the other way around. For example, a company can provide local PSTN numbers for their costumers to call wherever in the country they may be.

But what takes place is that whenever costumers dial any of these local numbers, their calls are automatically forwarded to the company’s PBX. With this situation, the company is able to provide hassle free and cheaper calls for their costumers.

The best thing about SIP Trunking is that it lessens the use of so many physical connections. Also, SIP trunks can actually handle multiple phone calls at the same time. But there are still chances that too much calls can produce heavy bandwidth traffic, which leads to blockage on the company's networking. So what most companies do is that they simply but multiple trunks to prevent such kind of problem from happening.

Once more, SIP Trunking can be availed from either an ITSP or ISP provider, so the company has options for their preference.