One of the best-known examples of wireless technology is the mobile phone, also known as a cellular phone. These wireless phones use radio waves to enable their users to make phone calls from many locations worldwide using techniques like CDMA, GSM etc.
GSM (Global System for Mobile Communications, originally Groupe Spécial Mobile), is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe protocols for second-generation (2G) digital cellular networks used by mobile phones. GSM supports voice calls and data transfer speeds of up to 9.6 kbps, together with the transmission of SMS (Short Message Service).
Using AT Commands
AT commands are instructions used to control a modem. AT is the abbreviation for attention. Every command line starts with AT.
Table1: AT Commands for Calling
|ATD <Number>;||To dial a number|
|ATA||To attend a call|
|AT DL||To redial the last number|
|ATH||To Hold the call|
Table2: AT commands for Messaging
|To enter text mode|
|AT+CMGS = < Recipient Number>
(Then press Crtl+Z)
|To send a message|
|AT+ CMGR= N||To read Nth message|
|AT+CMGD = N||To delete Nth message|