howto-howto: Checking if the GSM/GPRS Modem or Mobile Phone Supports the Use of AT Commands to Send, Receive and Read SMS Messages

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Checking if the GSM/GPRS Modem or Mobile Phone Supports the Use of AT Commands to Send, Receive and Read SMS Messages

forex AT Command Wednesday, January 13, 2010

After testing the communication between the PC and GSM/GPRS modem/mobile phone, the next thing that you may want to do is to check if the GSM/GPRS modem or mobile phone supports the use of AT commands to send, receive and read SMS messages. Most GSM/GPRS modems support all three functions. However, only some mobile phones support all of them.

Sending SMS Messages

To find out whether a GSM/GPRS modem or mobile phone supports the sending of SMS messages through AT commands, you have to:

Use the AT command +CSMS (command name in text: Select Message Service) to check whether mobile-originated SMS messages are supported.

Perform test operations to check whether +CMGS (command name in text: Send Message) and/or +CMSS (command name in text: Send Message from Storage) are supported.
(You may want to check the AT commands +CMGW [command name in text: Write Message to Memory] and +CMGD [command name in text: Delete Message] in addition as they are sometimes used together with +CMSS.)

Receiving SMS Messages and Reading SMS Messages from Message Storage

To find out whether a GSM/GPRS modem or mobile phone supports the receiving and reading of SMS messages through AT commands, you have to:

Use the AT command +CSMS (command name in text: Select Message Service) to check whether mobile-terminated SMS messages are supported.

Perform test operations to check whether +CNMI (command name in text: New Message Indications to TE), +CMGL (command name in text: List Messages) and/or +CMGR (command name in text: Read Message) are supported.

If the GSM/GPRS modem or mobile phone supports the +CNMI AT command, it can send a notification or directly forward the message to the PC whenever a new SMS message arrives.

If the GSM/GPRS modem or mobile phone does not support +CNMI but supports +CMGL and/or +CMGR, the PC has to poll the GSM/GPRS modem or mobile phone repeatedly in order to know if any new SMS messages have arrived.