I am using a SIM800L connected to an arduino mini. I have attached some sensors and when sensors go high I get an SMS message. When I use a PAYG Vodafone SIM in the sim800l, with credit, it does not send any SMS messages. When I use a contract Vodafone the messages are sent without an issue. When I insert the payg sim into a phone I receive configuration messages for mms sending. Could the configuration message stop the sim800l sending an SMS?
If I use the command at+ cmgd=1,4 would that help solve it ?