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What is SIP Trunking and Can it Save My Business Money?

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If you are the proud owner of a SIP compatible IP PBX and are currently using a PSTN (Telkom) connection, such as a PRI or a handful of lines to make and receive phone calls, it might be time to give SIP trunking a look. Many IP PBX systems, such as Asterisk, Cisco, Mitel, and a few others allow you to leverage SIP trunking, in addition to maintain PSTN connectivity. By editing the dial plan in your IP PBX, you can dictate which types of calls you want to connect to the PSTN, and which calls you want to hand off to your SIP trunking provider for termination. Cost savings is a primary reason why SIP trunking is becoming increasingly popular with businesses of all shapes and sizes.

What is a SIP Trunk?

For enterprises wanting to make full use of their installed IP-PBXs and not only communicate over IP within the enterprise, but also outside the enterprise a SIP trunk provided by an Internet Telephony Service Provider to connect to the traditional PSTN network is the solution. Unlike in traditional telephony, where bundles of physical wires were once delivered from the service provider to a business, a SIP trunk allows a company to replace these traditional fixed PSTN lines with PSTN connectivity via a SIP trunking service provider on the Internet.

Why would I want SIP Trunking?

There are a number of reasonable answers to that question, but the primary advantage for many users is cost savings. For example, as a business owner, I could leverage SIP trunking to bypass expensive Long Distance or International toll charges levied by my PSTN provider. The rates for domestic, mobile and international calls are typically a fraction of what can be charged by traditional Telco operators. Understanding that a SIP trunk is dependent upon the integrity of your data (internet) connection, it is often prudent to use SIP trunks to complement traditional PSTN circuits. This gives you the cost savings you are looking for, in addition to the fail-over and redundancy of having two call carriers available.

How do I setup SIP Trunking on my IP PBX?

Actual trunk configuration will vary depending upon the make and model of IP PBX you are using. For specific configurations please contact us and we woud be happy to assist. In a nutshell, you need to configure SIP trunking using account specific information obtained when you sign up for service with a Service Provider such as Voice and Data, AVOXI, Telviva, Internet Solutions, etc.

Next, modify the dialplan in your PBX to set up specific call rules which dictate which trunks (SIP or PSTN) calls are placed on when a user picks up a phone in your office and dials an outbound call. A very simple dialplan setup would use PSTN trunks for local calls, and SIP trunks for long distance or International calls. Many businesses with multiple domestic and international locations use SIP trunking for intra-office calling as well, often leveraging their existing data infrastructure.