some dsl and voip questions

[kobem]

anyone interested in voip i mean voice over ip

first my confusion is i think if there must be an internet also there must be
a computer over there . Is this true ?

and for voip: if we get to do voip in a company and we should have voip devices
in it then i want to communicate the analog phones between two branch offices
is it enough to have just voip gateways ?

another thing if we try to use voip phones what will change? can we use voip phones
without computer support ? i have seen somewhere "you can use voip phones
everywhere while travelling or... but how can it connect to the internet while
travelling?


last one is for dsl : i mean adsl ; while connecting from home to the internet
via dsl we use telephone line from isp and an internet cable for dsl and internet
ok then we use fast ethernet for modem to pc connecting.

if we want to do voip in a company across dsl how can we perform it ? do we
need a computer again?

schema :

analog phone - adc - voip device - router-modem - isp - modem-router - voip device-dac - analog phone is this right and where would be the dsl here?