Airtel
Number discontinued and allotted to somebody else

I was using Airtel prepaid number from past 9 years. As I was away | could not use the number and found when checking after three months that it has been suspended and allotted to someone else.

May please know

1. What is the maximum time a number can be continued without using the same.

2. How I can retrieve the number back.

Regards,

Airtel Custome