Arduino Forum

Using Arduino => Networking, Protocols, and Devices => Topic started by: ceskk on Apr 01, 2020, 02:19 am

Title: SIM900 AT commands
Post by: ceskk on Apr 01, 2020, 02:19 am
Hello everybody,
I tested a GSM module using a FTDI adapter between SIM900 and PC. I tried and sent a SMS and it worked. On Terminal I received: "+CMGS:38 +CMTI:"SM",13 and I found the SMS on SIM card (I used the same SIM card as both sender and recipient).
Few days later I tried again and it didn't work and I received on Terminal: "+CMGS54 +CMT:<tel num, time>
What may be the problem? I underline the different answer I received on Terminal: +CMTI and +CMT

Thanks in advance