If opted for Mobile Number Portability(MNP), Mobile Subscriber may shift to one of these Telecom Operators, but subscribers can not change circles.
New Mobile Tracer Application Details:
Trace Mobile Location is a FREE Application. You can use this for tracing or searching any Indian Mobile Number in 10 digit format. This program shows you Location of Mobile Phone on the map. Results will also show Telecom Operator and Signaling used by Mobile Phone. We have complete database of all the Indian Telecom operators. All the Indian Mobile Numbers are traceable through this program now.
Here is Complete Indian Mobile Directory