I am using paytm since 2012. friends must have this app. Because this app support all recharges that may be prepaid . You can even pay postpaid bill , Gas bill , metro .You can even see the plan available for a number , and most important it is not only a recharging website, it is like a online shopping website you can buy any product listed over there , But one thing upsetting that delivery is not so fast and some time the product vary as per not by order . but customer support is satisfactory.
Apart from this paytm also support wallet u can make payment through wallet and either by other major payment that is debit card . credit card , net banking .
Other advantage of this application is that even u can transfer money to any account but they are charging 5% as service charge , and minimum amount that can be transfer is limited to 500 . this is the negative point