I have a GSM/GPRS shield for Arduino. It uses a SIM800 from SIMCOM. I've done several projects using it. Previously I used to send SMS from the same module. which were delivered appropriately. Since yesterday, whenever I am sending an SMS to my Android mobile, all what I receive is:

<<Content not supported>>

I also tried sending it to a basic mobile. It displayed:

Content can't be displayed

I tried changing the encoding using the AT command.


It didn't work for any encoding.

The command I use to send SMS is:

---> AT+CMGF=1
<--- OK
---> AT+CMGS="10 digit number"
<--- > 
> Hello!

Can someone please tell me what is going wrong? Thank you in advance!

1 Answer 1


In the SIM900 is an AT command that let you do a factory reset, your module will restart to the default values. It must be an AT command very similar to the SIM800.

The AT commando that (perhaps) will work for you is the ATZ, in the SIM900 works for me.

You can look over here to see what command is. Look over page 33. And be carefull, the link that I send to you is the AT command list for the SIM900, not the SIM800.

Hope you can find an answer.


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