Hi Raj,
To do this you need to set up a five setas facility in India, based on VoIP
For this you will require an Internet feed on both the ends connected to VoIP Gateways.
In UK the calls will land on your regular phones and get routed through EPBX and gateway into the Internet and get delivered at India end on IP
In India call will go thru route and gateway into either EPBX OR directly to agebts who will then take care of the call
Pankaj Garg