Are you using Airtel and you don't have sufficient air time credit on your device, this December you will learn how to flash any number for free on your phone without the need of credit on that particular simcard. This tricks works on all Airtel sim card either its new or an old sim card.
The main aims of the trick really serves you incase you have run out of credit and you want your friend to call your number back within a min. As i aside earlier about this trick, its only work on Airtel sim only, but you can use the sim to flash any number using these below method.

- How to Flash Any Number Without Airtime with Your Airtel Sim

First of all, you will need to copy out the number you want to call out from your device.

Then Go to your phone dial-pad,  quickly paste or type the number there. 

Make sure you Add "**" at the beginning of the number. (Eg) **09033474141

Call the number, it will disconnect at your own end and It will ring once at the receivers end. 

That's All, You have flashed the number without having any credit on your phone. 

You can repeat it to keep flashing the person. You can also use the above steps to flash another network number fron your Airtel line. 

This trick currently works with Airtel only and it doesn't have limit. You can do it as many times as you like.