VoIP, or Voice
over Internet Protocol, is a
method for taking analog audio
signals, like the kind you hear
when you talk on the phone, and
turning them into digital data
that can be transmitted over the
Internet.
How is this useful? VoIP can turn
a standard Internet connection
into a way to place free phone
calls. The practical upshot of
this is that by using some of the
free VoIP software that is
available to make Internet phone
calls, you are bypassing the
phone company (and its charges)
entirely.
Basics:
Sending a signal to a remote
destination could have be done
also in a digital fashion: before
sending it we have to digitalize
it with an ADC (analog to digital
converter), transmit it, and at
the end transform it again in
analog format with DAC (digital
to analog converter) to use it.
VoIP works like that,
digitalizing voice in data
packets, sending them and
reconverting them in voice at
destination.
Digital format can be better
controlled: we can compress it,
route it, convert it to a new
better format, and so on; also we
saw that digital signal is more
noise tolerant than the analog
one (see GSM vs TACS).
TCP/IP networks are made of IP
packets containing a header (to
control communication) and a
payload to transport data: VoIP
use it to go across the network
and come to destination.
Last comments: October 2016
Voice (source) - - ADC - - - -
Internet - - - DAC - - Voice
(dest) last comments: July 30 2017
