Not able to send SMS with SIM800L - Call is working

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Aswinth Raj's picture

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Not able to send SMS with SIM800L - Call is working
January 22, 2021 - 2:28pm

I got myself into a rather strange problem while working with SIM800L through AT commands. I am able to place calls and even read messages but when I send a message 

using putty terminal  

AT+CMGF=1

AT+CMGS= "+91XXXXXXXXX" [ENTER]

> sample message [Ctrl+Z]

I get the following response 

Everything looks good on the terminal, but I did not receive a text message. Surprisingly I also noticed that my network provided (Airtel) has also charged me for sending an SMS but I never did receive it on any number. 

Solution:

After digging into the AT command spec sheet of SIM800L I found that we have to set the message type using the following command

AT+CSMP=17,167,0,0

This has solved my problem :-)