In my country there are some numbers to which we dial, for example: (HONDURAS)
#123# (send) and the service provider send a special message (not sms, just like a pop-up windows) with your prepaid balance.
Also if we want to give money from our balance to another user balance we dial
*327*the-phone-number-to-which-we-want-to-send*amount-in-numbers-that-we-are-sending#(send)
then a message appear confirming our request, we send 1 for yes as text message or 0 for no or just cancel.