How Does SIP Trunking Work

SIP Trunking uses Session Initiation Protocol (SIP) to establish voice communication between an Internet Telephony Service Provider (ITSP) like Broadvox and a business IP PBX. ITSPs provide business VoIP communication over the Internet. The connection of an ITSP is different from an Internet Service Provider (ISP) connection because voice communication is enabled with a SIP trunk, and an ISP can only provide an Internet connection. Broadvox is a business VoIP provider with expertly engineered IP telephony products that offer greater reliability, features and functionality than the public Internet. Businesses are able to migrate to IP Communications from traditional TDM gradually, using their legacy CPE with a SIP PSTN gateway or all at once with an IP PBX. This flexibility allows communication between any device that is IP enabled, including SIP phones, smart phones, PDAs and computers.

Historically, voice signals traveled over physical wires but SIP Trunking makes a logical connection from one point to another through the Internet, making it possible to treat IP voice communication as just another application and deliver it as packets of data. The goal is to have the voice signal travel on the worldwide Public Switched Telephone Network (PSTN) as little time as possible because the cost of using those physical wires is much higher than the virtually free Internet. The Broadvox GO! SIP Trunking price provides seamless access between the Internet and PSTN, resulting in immediate cost savings because calls travel the majority of the distance on the Broadvox network, avoiding the high cost of the PSTN.

As shown in the diagram, it is possible to avoid PSTN charges altogether if both the originating and receiving parties use Voice over Internet Protocol (VoIP) for voice communication. If both parties use SIP services to establish voice communication, their calls can travel on the Internet for virtually no charge. The only charge would be a reduced rate charged by their ITSP provider.

When companies use Broadvox GO! SIP Trunking services, calls travel the majority of their path over the Broadvox IP Network instead of on the PSTN and then they drop back down to the destination/facility at the last mile (the physical line between the local phone company switching facility and the destination of the call). If both companies use Broadvox GO! SIP Trunking, then the last mile connection to the PSTN is not necessary. Implementing Broadvox enterprise SIP Trunking dramatically reduces local and long distance charges because calls spend a very limited amount of time and distance on the PSTN. The less time a call spends on the PSTN, the lower the cost will be.

For Example: A Broadvox VoIP SIP trunking user places a call from Texas to Cleveland, Ohio to a destination that does not use IP Communications. The call travels over the Broadvox IP network and is then “handed” to the PSTN at the last mile for delivery. In this case, the PSTN would be in Cleveland or the city closest to the destination. Since the call travels primarily over the Broadvox IP Network, the long distance call rate is a fraction of what it would have been if the call had been placed over a traditional phone line.

SIP Trunking Benefits and Best Practices” by Janne Magnusson of Ingate® Systems.

Click here to read about further benefits of SIP Trunking.

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