TRAI has released recommendations [DoT is likely to accept them with some modifications] permitting ISPs to offer unrestricted internet telephony [permitting them to terminate calls on PSTN/PLMN networks]. Until now only international VoIP telephony was legal. NLD operators shall be permitted to connect to public internet and shall have mutual agreement for unrestricted telephony.
Telephone numbering scheme from identified blocks to be made available for internet telephony. Shortcomings of the recommendations are, Emergency Number calling and Quality of service are not mandated.
In 1999-2000, NLD / STD Tariff per minute was Rs 30 and today it is at Rs 1.0 which is likely to fall further with the introduction of VoIP telephones. By 2010, you will have unlimited / heavy calling plans [5,000 minutes or Night Weekend Free Calling] on your mobile within India 🙂
Update: It is likely that most Telecom companies will introduce calling cards where they will route the traffic on IP networks thus enabling them to launch products faster into the market.