Since the calls will be originating from UK and terminating/landing up in INDIA. As of now we have a single international gateway for all voice calls in INDIA and all calls are routed through this gateway. But once the calls land on our gateway in INDIA , there will be no problem for the calls to route to your call center in INDIA. So nothing much is required from INDIA except some connectivity and muxes for the IPLC and of course your Call Center needs to be in place and equipped with all the infrastructure.
As far as INDIA is concerned , we r still developing on the concept of TOLL FREE NUMBERS. We have a level of 1600-XXXX in INDIA. This may come as a surprise to u , WE DO NOT HAVE NATIONAL ( WITHIN INDIA ) TOLL FREE NUMBER IN INDIA YET. But with the entry of private long distance service providers , this facility of NATIONAL TOLL FREE is promised by them. Let us see how soon we can have it.
I hope I have cleared all your doubts/queries/concerns. In case u have more queries , please feel free to get in touch with me.