Tata Docomo — How do I re-activate my old Tata docomo number which still says invalid when dialed.

Address:

hyderabad

Hello Docomo Support,

Could you help me in getting the number re-activated. I have missed this sim long ago and during my house vacation, i have got this sim back, now when i dial this number it says number invalid. I know this cant be ring as it was not in service sice long time. But i would like to know the process to get this number active again.
Tata docomo number: [protected]
i heard that tata docomo was sold to Airtel. Now i am not sure to which store i have to visit to get this prepaid number activated.

Regards,
Rajkumar Bollam
[protected]@gmail.com