India used to be and still is split into several telecom regions with different spectrum leasing, operations and governance.
Until around 2009-10, when you are traveling out of state, you had to pay roaming charges. Worse used to be metro cities within their own states as they used to be different telecom circles. I used to pay roaming charges when going to Chennai from rest of Tamil Nadu. Even the operators were different sometimes. E.g. there was no Hutch (now Vodafone) originally in rest of Tamil Nadu and they operated only in Chennai. Similarly RPG (later Aircel which went bankrupt couple of years back) had 2 networks - RPG in Chennai and Aircel in rest of Tamil Nadu. It used to be a mess.
No operator had pan-India operation as every small operator had their own fiefdoms and the big operators like Airtel used to pay roaming charges to those operators for their subscribers to get signal.
Until around 2009-10, when you are traveling out of state, you had to pay roaming charges. Worse used to be metro cities within their own states as they used to be different telecom circles. I used to pay roaming charges when going to Chennai from rest of Tamil Nadu. Even the operators were different sometimes. E.g. there was no Hutch (now Vodafone) originally in rest of Tamil Nadu and they operated only in Chennai. Similarly RPG (later Aircel which went bankrupt couple of years back) had 2 networks - RPG in Chennai and Aircel in rest of Tamil Nadu. It used to be a mess.
No operator had pan-India operation as every small operator had their own fiefdoms and the big operators like Airtel used to pay roaming charges to those operators for their subscribers to get signal.
This all slowly went away only early this decade.