ClaesBr:
I have the same problem with the Efcom Pro 1.0 module and a Arduino Uno Rev3.
Nothing of the above solotions works.
Has anyone been in contact with Elecfreaks to solve the problem? They built the module, so they should be able to answer what we should do about it. I'm going to give up soon.
At this point I'm going to. I have 2 of their units. I cant get either to work, when they both worked absolutely fine before using AT commands via serial connection via my Uno and PC. In the interim picked up a similar unit from TinyOS Shop and it works. I could only get it to work at 2400 baud, but that is fine by me. Based on the number of folks having very similar issues, I assume this is a SIM900 related bug.