如果GSM调制解调器上没有网络怎么办

Question

I have to send a message for every minute, I'm using telit GE864-GPS modem, my modem will be used in remote places, so my device will write data into GSM modem, and if the message is submitted to destination successfully, I will get a response as +CMGS:, what happens if msg is not submitted to destination due to no network available. "will the modem retry to send that message", how to find that network is available for the modem.

Answer 1

The answer to AT+CREG? will tell you if the device is currently registered on a network. If it's registered on a network, you can send SMSs (assuming your contract allows it). AT+CREG is documented in 3GPP TS 27.007, available from the Specifications page of www.3gpp.org.

A quick glance at the 3GPP test specifications shows, that there is no test for the behaviour of an MS (GSM modem) when trying to send a mobile-originated SMS if there is no network. Tests are described here: 3GPP TS 34.123 part 1, section 16.

Therefore, the quickest thing to do is either (a) ask the manufacturer or (b) just test the behaviour of the device yourself. Go somewhere without a network, try and send an SMS, wait, go back to where there is a network, and see if the SMS gets sent, what does the device return after a reasonable timeout etc.

Once you know the behaviour of the device, you can design your code, based on checking if there is a network before you send the SMS, waiting for +CMGS and probably a timeout in your code.