11-19-2002
n/a,
0
R. Prabhu,
if this is home work , You have missed FAQ and rules of this site. check them out first.
Simply speaking , pstn networks can use unix "gateways" to transmit voice over I.P.
that is if u have backbone for pstn ready , than this is what happens:
caller A picks up a phone , gets dial tone (from PSTN backbone)
dial a no of reciver B. The gateway server uses TCP /IP , which sends this signal as packet based ,to another Gateway node in IP world , which than looks at this package , decides which destination gateway can handle this package (or telephone no),
forwards it there , than that gateway sends that package to reciver B. and call is completed. As I.P is Packed based ,there is no dedicated connection , that is every one can use same connection . where as in PSTN pure network , one a link is established , it can not be used untill free.
regarding coding , i dont know. But You got to write a code , how to connect to or "dial in" ( i think using cu "tel no" command)to a getway server.
good luck