I am trying to use a ZTE MF620 modem with an AT&T goPhone SIM in the USA with the Windows (XP) version of FrontlineSMS 1.4.8.
In fact, this is the very same modem mentioned here
When I run FrontlineSMS after having closed the ZTE app, the modem is recognized, the number is read properly, but it fails to connect. I get "SIM card invalid.: GSM network registration failed." It sounds like Sean was getting this problem in Indonesia as well.
Would anyone be able to identify under what circumstances that error occurs? Is the issue with the modem being locked to a specific provider (what this
thread seems to suggest)? Is it with the device itself being blocked by providers?
Thanks very much for your help.