Understanding Voice Over IP Gateways

by Andrew Wiggin⁽²⁵⁾
http://www.onsip.com

There are two components to any VoIP system. The first, deals only with issues occurring within the IP network itself. Problems like addressing, signaling, codec negotiation etc. are determined based on the same underlying IP architecture. The advantages offered by VoIP range from superior sound quality, free communications within the IP network itself, and any other innovative application which can be coded into the network. SIP forking is one good example of behavior which is impossible to replicate on PSTN devices. But a lot of these advantages are lost when communicating with someone who is still using the POTS. This is because benefits such as HD voice depend on the use of better quality codecs which cannot be transferred to regular telephones. Moreover, as soon as the call makes the transition from the VoIP network to the PSTN, it incurs costs.

But the benefits of being able to integrate with another network are so great, that the loss of these features is worth it. The real challenge is to convert the VoIP signals into one that is understood by the traditional telephone networks. This is difficult for many reasons. The biggest one is about making the transition from an IP-based network to one that works on circuit switching. The point at which this transition happens is known as a VoIP gateway. Without this component, VoIP users will be locked in to the Internet world - unable to make contact with anyone outside it. The gateway exponentially enhances the power of VoIP by allowing it to reach out and talk with billions of users still on traditional phone networks.

One major consequence of this integration is the use of telephone numbers instead of SIP addresses. Telephone numbers are vital for anyone attempting to work with the PSTN system since it understands nothing else. VoIP being the new kid on the block, has to accommodate itself to use the addressing system of the traditional phone networks. Within the IP network itself however any two users can connect to each other for free utilizing their SIP addresses in very much the same way that they would use an e-mail address.

This single point of transition between VoIP and PSTN actually leads to several problems since it is easy to control a choke-point. Governments all over the world have varying degrees of restrictions on VoIP traffic and either don't allow VoIP gateways to exist in their countries at all, or heavily regulate them. One can only hope that going forward, VoIP becomes as ubiquitous as the Internet itself without any restrictions imposed by governments.

Andrew is an IT and Voice over IP expert. He specializes in hosted VoIP and hosted PBX solutions for businesses that want a 'corporate'-style phone system at a fraction of the cost.

Article submitted Tuesday, January 24, 2012 & read 3 times.

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