Switch to a nation carrier like Airtel, BSNL, Tata docomo etc.
Don’t go with local carriers who are shutting down their networks in many areas without even informing the customers.
So switch to one of the big mobile providers while you can using MNP.
I had to go through this recently when Aircel stopped service in my area without notice. I went for two week without mobile while i switched to Airtel network. All the while fearing my phone number would not be lost, luckily i was able to get the same number.