Every couple of days someone comes to me with a question about their cellular phone. How do I check my balance? How do I transfer credit from my phone to another? How do I reach customer service? What is Plan Amigo? What's the difference between saldo principal and saldo de bonos? How come my credits disappear? Can someone steal credit from my phone? (The answer is no.) And so on, and so on.
So I put together a list of all the codes, commands, and functions that I know of for Tigo, Claro, and Movistar cellular phones, along with instructions on how to use them, and some advice and suggestions, and put it all together here in English and Spanish on a single web page.
I hope you find it useful.