I'm trying to develop an application to send SMS, using AT commands. For testing purposes I have two Nokia 6310i phones, on one phone the application is successful, on the other, it will sparadoically work.

The only difference I've been able to find is that the working one the firmware version is:
V 5.50

and on the other the firmware version is:
V 4.81

... This appears to be the major difference between the two phones, and I think it's the problem my program is running into.

Is there somewhere I can go to find more information about firmware version, and possible known bugs?