Whatever they may tom-tom about the rates or quality of service, none of the cellular operators have offered reasonable roaming rates. Airtel's roaming rates are one of the highest in this country!
Moreover, the subscriber has to bear the brunt of the cost of incoming or outgoing call. So, I have a suggestion to make, though it may or may not be technically feasible. I give the following scenario as an example:
Suppose a person is a subscriber in Andhra and a frequent roamer to Karnataka. Most of his contacts are in Karnataka. Prior to his travel into Karnataka border, he activates roaming.
When he has crossed the border and if there is an incoming call from Andhra, the calling party is informed by IVRS that since the subscriber is out of the state border, this call is bound to be an STD call. Press 1 to continue the call; press 0 to end the call.
Suppose the roamer is in Bangalore and makes a call to a mobile number in Bangalore, he is charged nearly Rs. 4 per minute. This discourages the subscriber from using the roaming. This kind of call should be treated as local and routed via the roaming network hub instead of the home network.
