I want to know how many mobile companies are in Karnataka. Where should I file RTI for this?
It is not clear from your query as to its reference i.e. whether service providers or mobile manufacturing companies. \
For information on service providers, you could address your application to the Department of Telecommunications or Information Technology. For information on mobile manufacturing companies, you could address your application to the Department of Commerce or Industries, both of which are public authorities and are under the ambit of the RTI Act.
Under section 2 (f) of the RTI Act, you could obtain certified copies of the relevant documents and records.