How Voice Travels over IP

Voice traffic flows over the
network through a gateway that acts as a link between an IP network and a
telephone network. The gateway digitizes the standard telephone signal,
compresses it, converts it into packets and routes it over the network to
its destination.

The electronic transmissions are
chopped into packets of varying numbers of bytes. Each packet is given a ‘header’
or address label, and sent from one network node towards another. Each
packet is put into separate IP "envelopes" containing addressing
information that tells the Net where to send the data. All the envelopes for
a given piece of data have similar information so that they can be sent to
the same location to be reassembled.

As the packets are sent across
the Internet, routers along the way examine addresses on the IP envelopes.
They determine the most efficient path for sending each packet to the next
router closest to its final destination.

The packets thus arrived are
received by the second gateway, which converts the call back to a standard
analog signal and routes it to the receiver’s standard telephone. Both the
gateways reverse the operation for packets coming in from the network and
going out the telephone simultaneously and on real time basis, allowing a
full-duplex conversation.