Cannot remake GPRS connection if abnormally terminated

We are using the 1306B terminal module, with the standard OS

641b09gg.Q2406B 1339080 041604 16:04

Currently I am not using the AT Open route but trying to run our own stack in a datalogging device connecting via terminal commands, however the issue I have is likely to be common so I think will have seen by other developers so perhaps someone can help.

The problem I have is that I can setup a GPRS connection OK and negotiate a PPP connection and it all works fine. If the connection is terminated correctly (IPCP and LCP shutdown etc) then I can restart the GPRS connection later using ATD99**1#.

My problem is that if the GPRS connection is not shutdown correctly I do not seem to be able to get the modem back in a state where it will let me “redial”. If I send ATD99**1# I get “ERROR” or “CME Error:3” with extended errors on.

It doesn’t seem to matter what command you give it (lowering DTR, +++ followed by ATZ, then shutting down the GPRS connection with AT+CGATT, etc) the modem will not accept the dial command again unless a full modem reset is forced, e.g. AT+CFUN=1.

I also note (and this may be related) that when the connection is lost or DTR is lowered mid-call, that the modem does not signal loss of carrier (3) when conencted via GPRS as it should do and as is infered in some manuals.

Is this a known issue or does someone have a solution to this please, preferably with standard AT commands?

Andrew S

Have you find out you problem.?