VB.Net Comms problem

[Tym]

Not sure this is the right group - but here goes.

I kinda expect Dick Grier to jump in on this one ;-)

I've got a windows app in VB.Net 2005 which sends and receives text messages
via a USM GSM modem. THe app cycles to poll the modem for incoming SMS as
well as pausing this cycle to send...

Working absolutely fine... except....

After a given period of time, the app "looses" the GSM modem, and gets stuck
on the .write command when I'm trying my AT+CSQ command. If I re-run the app
it says the device isn't working properly.

BUT

I've I go to control panel, Phone and modem options, Modems - right click -
properties - diagnostics and query the modem - all is well. After this, my
app sees the modem fina again.

I'm using the serialport1 control and talking to com13 in this isntance.

How can I keep the port alive? what is happening?

Secondly, I have connected an olf moble phone the the PC via a cable. This
puts it on COM14. I can query this in hypertermian by selecting the port and
issuing AT+CSQ, and getting a response. However, if I try it in my ap -
CAM14 doesn't respond? What's the difference between Hyperterminal talking
to the port and VB.Net?? my VB6 app can send and receive to this port (or so
it seems to - sending AT+CMGF=1 results in an error code - in VB.NEt it
doesn't give a code at all. However, with exactly the same code, VB.NET does
responde to the USB on COM13 -

Tym