I’m trying to validate these modems for our software application, which needs to send/receive SMS and send/receive missed calls.
I have a TRM250 unit. Doing tests I can’t get the calls to work, even though the documentation refers to “Call Related Service Commands”. All of these commands return ERROR, and any incoming calls are rejected as “not available”. So, I understand that it does not have support for calls.
But, will the same happen with the TRM240? Can anyone make or receive calls with these modems?
SMS works without problem.
Voice calls on TRM250 are supported, but the compatibility is really dependant on the carrier, as the narrowband networks are usually not intended for voice calls, but rather low bandwidth data.
To initiate a call, use the command
The semicolon at the end is usually necessary.
To answer the call, once you see a
RING output in the AT command terminal, run the command
ATA, and the call will be answered.
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