How to find the Forgotten/missed mobile number of unused sim card

I st Method :

For Airtel

1. Dial *141*123# or *141#

2. you will get a message.

3. Reply with 3.

4.Reply 5 or 30.

  

5. Now enter your Known airtel Prepaid no (Your friend or relation's airtel prepaid mobile no).

6. Now Airtel has sent an SMS to your Known mobile no(Friend No) from your un-known mobile no or Sim card.

7. Check the SMS in your friends mobile which is sent by your unknown Mobile no.

2nd Method : (Very simple method) 

For Reliance, Videocon, Virgin, TataDocomo, Bsnl prepaid sim

Dial *1# (Working in Chennai)

BSNL : dial 24365

Idea   : dial *789#

Aircel : dial *888#