How it works

There are several protocols and methods for VoIP calls – the commonest standards are termed SIP and H.323 – but they all have some basic features in common. To the user phone calls are made and handled in the same way as they always have been except that VoIP phones often have more features available from menus and buttons than regular phones. When a call is dialed, the system takes the phone number, connects over the local network to whatever system is providing service.

That system figures out if the call needs to go into the regular phone network and if so switches it to a gateway that connects the call over the regular phone network. If the call can be completed without going over the regular phone network (the number dialed is also a VoIP system) then the provider system will route the call directly, performing protocol translation (to a different kind of VoIP) if needed.When traveling on the network, VoIP calls are treated like any other network data – they are broken down into little pieces of digital information (packets) and sent by whatever route the network determines to be fastest.

That means different pieces arrive and different times and out of order and then are reassembled back into the proper sequence at the destination. This is why the 100+ kbps transmission rate is needed – so that the signal can be sent and reassembled quickly enough so that human users on both ends don't notice any delay. It is also one of the weaknesses of VoIP – if the network goes down or has performance issues, so will your VoIP calls