Is there a possibility to preserve an unused Indian mobile number for a period of time?

I think you are misinterpreting what the Indian government regulation says. It does not require the carrier to deactivate your account after 90 days of inactivity, it only requires the carrier to not deactivate your account until it has been inactive for 90 days. What happens after 90 days is up to the carrier.

I use Airtel since it is the sole carrier with coverage where I have to visit, but my understanding is that with Vodafone you can keep the SIM alive by just keeping enough of a balance on the account to cover a Rs20/month charge while you are away. This Vodafone web page (see the note after "Step 3") seems to confirm my understanding. Leaving Rs200 in the account when you leave should cover you for a year.

That might not be the absolute cheapest way to keep the SIM alive but it is certainly the easiest and isn't particularly costly.

Update: the minimum recharge required is now above INR 75 for every operator, the earlier plans mentioned below are no longer valid. Check the operator's plans page before recharging.

Indian telcos have started deactivating SIM cards that aren't active (news coverage), and they no longer consider account balance for this, so all of the above answers are no longer valid.

To keep the SIM active, you have to keep recharging it to extend validity. Every network has cheap plans specifically for this. Airtel has a INR 23(€0.3) plan that extends validity by 28 days. Other networks like Vodafone have similar plans (INR 35 or €0.4).

You can recharge from websites like Paytm or Freecharge.

A more convenient way is to install the mobile app of your network (Airtel's app is called, well, MyAirtel) and login with your phone number. It shows you remaining validity and even sends a notification when it is about to expire, and you can recharge from the same app.

I have very easy and cheapest solution for you , actually you needs to recharge your sim with minimum amount of rupees 20 at every 3 months online , doesn't matter where u are.this is how you can keep your number forever,

According the rule ,if there is no activity occur in 90 days your sim will be deactivated, as you recharge your number the system think you are active user. Make sure you recharge your number on time without fail....

When u recharge your number the system will generate a SMS to inform that U have been recharge successfully.

It will cost u about 90 rupees /year. It is not necessary to use your sim in India or anywhere in the world , simply keep your sim with u in your pocket, when u get to India just start to use your Sim .

Source>>>>>>>my personal experience (AIRTEL USER)

Sk- AUSTRALIA

I'm a Vodafone prepaid user and I am easily able to access the network in the whole of EU (not only Germany). I am a merchant navy officer and I keep on visiting different countries aroumd the world the whole year, yet I seldom find any country where the service provider as huge as Vodafone doesn't provide its services. The cheapest way to keep your number active is just by calling the customer support of the state circle from where you bought the sim. E.g. For me its +919839098390(UP- East circle). It's totally free of cost and you just need to hear the IVR respond "Hello, Welcome to Vodafone! We are happy to help you." and then disconnect the call. This simple step counts as "usage" and will preserve your number for the next 90 days even if you keep it out of your device. It is practically free of cost. This is how I keep my number alive while roaming internationally. sometimes , I also recharge with international roaming packs from the my Vodafone app in case i want to use internet or make calls but that's not necessary to keep ur number active. Vodafone provides international roaming for more than 150 countries so you don't need to worry for mobile network unless you visit a country such as Pakistan. Happy to help.

PS: you can manually connect to one of the service providers available in Germany.

Don’t need to do anything just recharge with Rs 106 N u can get one year validity . So they can’t take any money from ur a/c after 90 days I use my same sim from last 10 years never got any Problem when I get India just top up with 106 .

I use my Indian Vodafone SIM here in UAE, It cost me few bucks.. buts that are ok The scenario is: I do Rs.222 recharge in every 3 months (from my SBI internet banking or you can say anyone in India to recharge for you) and I make just 1 call in every 3 months to any friend in India for 1 minute or less than 59 seconds which cost me Rs.140 per call - voila. .. done... don't make any call until next three months.. and no further recharges till then.

Received free miscalls from friends and family in India. Receives free sms from your friends and family in India or Banks OTP etc. keep your number active forever.

Note: Before completion of 3 months., you will get SMS from Vodafone to " Make a phone call to keep your number active" So., no need to keep a reminder when to recharge next.

hope it helps.

try this, --ANDROID PHONE--

** make sure you have min 100Rs balance and a 249 international roming pack (Germany) active

1. in the app page of your phone check for an app that has a Sim-card like logo named "Vodafone services"
2. once you open the app click on roaming and select international
3. you may have to restart/switch off &on your phone
4. once this is done go to your sim settings under settings, select vodafone sim and click carriers
5. set it to manual if its automatic and it will start searching for networks
6. click on Vodafone.de4g or Vodafone.de2g
7. It should connect even if its says its forbidden