Everything There Is to Know About SIP Trunking - Part I

SIP makes use of what is called the "trunk" through which the communication is channelled. The SIP trunk can be connected to an internal PSTN (public switched telephone network) line, through which companies can communicate through their IP PBX system to the outside world. In fact, with SIP, companies can replace analogue circuits and fixed PSTN lines with a more efficient IP phone system to create a converged line for multimedia communication.

How does SIP Trunks Work?

As explained earlier, trunking basically converges voice (multimedia) with data into a single, managed line. The trunk converts signals from the phone system to data through Internet connectivity, allowing the data network to actually handle voice traffic. With this merged line, local and long distance calls can be supported at lower rates; directory listing, E911, multimedia conferencing and caller ID can also be integrated into this system.

To give you a better idea how VoIP Trunks work in real life scenario, you can imagine this. Say a sales representative in Washington DC has to make a call to a client in Paris. In traditional PSTN lines, this call may cost a few pounds per minute. With SIP integrated in an IP-PBX system, this call will either originate as an IP call or may be converted into one, then the call is routed to the Internet service provider, then transferred back to the PSTN network as it is terminated. Most of the call is being made in the IP network which means that you will not be charged hefty fees for international dialling.

The Benefits of SIP Trunking

SIP Trunking is considered state of the art in telephony solutions because of the many benefits it offers. Among SIP trunking benefits are as follows:

1. SIP does away the need for purchase of TDM-gateway or desktop equipment, as well as the need for managed media devices that interfaces PSTN with IP.

2. SIP eliminates the need for BRI or PRI connections which can telephone costs to a minimum.

3. With SIP, companies can outsource their PSTN, which means significantly reduced costs for making long distance calls.

4. SIP is highly scalable which means it can be used for as few or as many a user. The system can accommodate even large growth of communication lines with minimal cost expenditure.

5. SIP features points of presence even in different locations (customers dial local numbers to get to you) with lines more efficient that 1-800 toll-free numbers.

Cost of SIP Trunking

SIP Trunking is significantly cheap relative to its functionality and benefits. Yes, SIP requires purchase of IP PBX systems or IP phones and other similar infrastructure (if the company doesn't have one existing yet). However, with this cost- effective methodology deployed properly, return of investments can be expected in no less than 6 months.