Q: What are AT commands?

AT commands, also called Hayes AT commands, are based on the Hayes Modem de facto standard, ATTENTION Commands for modems. They are used to communicate with your modem. These commands modify your modem's behaviour or instruct the modem to do something specific, such as dialling a telephone number. The "AT" refers to getting the ATtention of your modem.

Here are some typical reasons using AT commands: