I travel to India a couple of times per year. I purchased an Indian SIM card and I find that there is no network for this Indian service provider in Southern Germany (Friedrichshafen/Konstanz). And as per Indian telecom rules, the service provider deactivates a number that is not in use for more than 90 days.
I would like to know if there are any method to preserve my Indian number when I am in Germany and not using the Indian number. For further information, the Indian service provider is Vodafone. And the plan is called a prepaid connection (for people who are familiar with the Indian telecom system).
What is the cheapest way to preserve my number? Or what is the cheapest alternative? German telecom companies charge heavily for roaming and I have no interest in using them in India.