Use these codes to forward calls, pay your bill, check balances, etc. Some of the codes work only on certain carriers or devices. One of the codes also might erase your data, so use with caution. I've ...

To enable call waiting on an iPhone, go to Settings > Phone > Call Waiting and toggle the switch on. On an Android phone, you typically open the Phone app, then go to Settings > Calls > Supplementary ...

Coders have a storied tradition of creating back doors in programs (or sometimes just fun little Easter eggs) that can only be accessed with a special "key." This has happened for almost as long as ...