squirdle
First thing to do if a sim doesn’t work in any alarm or similar device is to test it in a phone. Phones have greater diagnostic ability, and because we all have phones, it’s more likely that a helper will be able to recognise a problem and solve it.
But if the sim works properly in a phone, then it would help to give us the model number of the alarm (or better still, a link to the alarm’s online instructions) and an example of the actual commands you’re trying to send, so that we can try to work out what’s going on.
