SIM900 - Faulty?


I have been working on my first SIM900 board hooked up to an Arduino and something doesn't seem right.

It can be very unreliable although when it works, it works. So my syntax and baud rate etc is all fine.

Sometimes though it will just become unresponsive. I may have to send AT a few times to get a response and some times it will get into a state where it only replies with the command I have sent it (even with just the AT command) but no "OK" or "ERROR", just what I send it.

I have also noticed that sometimes when I boot it up and it sends out some unsolicited data it gets to a point and then stops.

+CSMINS: 1,1
+CFUN: 1

Cal I presume should have continued to be "Call Ready"

Could it be down to the PSU I am using to power it maybe?

Currently, for testing purposes, I am plugged into the mains with a 9V 1000ma PSU.

Actually now I've looked at this I think I remember reading that it can require higher amperage when it is doing stuff.

But that would cause it to reboot right? Not just sit there echoing what I send it?

Any help/advice appreciated.

Wow, that got buried pretty fast!


The problem is probably either in the code, or the wiring.