I spent some time this afternoon looking for a bug in some code… I eventually found it – the error was that to send an SMS message, you need to send the following commands…
This is the message[Ctrl-Z]

The problem was that the Ctrl-Z was being sent incorrectly… In VB you need to send it like
SendText (“This is the Message” & chr(26))
The code was actually something like
SendText (“This is the Message” & “/n001b”)
which did not work. I eventually found this by accident… When the modem refused to respond.