In case you send me your email id I can mail you the Real Time
Internet Protocol (RTIP) Network Topology.
I would like to add here that VOIP is allowed in India only in a
closed user group environment and is being used as such even
today by companies, however, the moment you connect to the
PSTN and route the ISD calls through VOIP you are violating the
law and that is a serious offence in India.
We expect Internet Telephony to become legal wef April 2002.