Fatal problem with Q2406A

#1

Good day.
We have a 150 devices equipped with Q2406A “without simcard”.
Device reports about itself:
at+cgmi
WAVECOM MODEM
OK
at+cgmm
MULTIBAND 900E 1800
OK
at+cgmr
543_09gg.Q2406A 1364028 020305 19:10
OK
at+whwv
Hardware Version 4.75
OK
at+wssw
a04_48gg.Q2406A 0006002CAB5DC7EA
OK
at+wdop
Production Date (W/Y): 26/2006
OK
ati
WAVECOM MODEM
MULTIBAND 900E 1800
OK
ati3
543_09gg.Q2406A 1364028 020305 19:10
OK
ati4
Q:0 V:1 S0:000 S2:043 S3:013 S4:010 S5:008
+CR:0 +CRC:0 +CMEE:0 +CBST:0,0,1
+SPEAKER:0 +ECHO:0,1 &C:1 &D:1 %C:2
+IPR:115200 +ICF:3,4 +IFC:2,2
OK
ati6
DATA RATES: AUTOBAUD,300,1200,1200/75,2400,4800,9600,14400
DATA MODES: T/NT,ASYNCHRONOUS
FAX CLASS: 1,2
OK

We use it as a usual GSM/GPRS modem via RS232 inside a device.
Protocol uses DTR signal and commands
AT&FE0V1+CREG=0
AT+CMEE=1
AT+WAIP=1 (optional mode)
AT&W (optional mode)
AT+CFUN=1 (optional mode)
AT+CREG?
AT%C0+CBST=0
AT+CGDCONT=1,“IP”,“internet.usi.ru
ATD
+++ (in no DTR mode)
ATH

Over 50 modems get out of order (we think - main software broken). Modems just stopped responding to any command or DTR signals.
Device manufaturer can’t find out the problem and said that the problem is local - just with our software (or our local sim card type or radio conditions).
I’ve created a data/signal exchange log.
I found that modem sometimes can’t register in network and may stop respond to AT+CREG?
or AT+CFUN=1 commands. But after a while it start respond again.

AT&FE0V1+CREG=0
< OK
AT+CMEE=1
< OK
AT+CREG?
< +CREG: 0,0
< OK
AT+CREG?
< +CREG: 0,2
< OK
AT+CREG?
(oops! no answer! but later we will get it)
timeout
AT&FE0V1+CREG=0
(still no answer! but later we will get it)

In a 2 logs of broken modems the fatal command was AT+CFUN=1
SET_DTR:
SET_DTR:

AT&FE0V1+CREG=0
< OK
AT+CMEE=1
< OK
AT+WAIP=1
< OK
AT&W
< OK
AT+CFUN=1
!!! (this is the last fatal command, but previous +CFUN=1 were successfull or non-fatal. What can I do wrong here or later?)
If I do not use +WAIP & +CFUN modem fails (forever) on (I think) start up or shut down.
Note: problems are under hard radio conditions - modem can’t or hard to register in gsm network.
We use the same protocol on other devices with other modems (or this device with other modem), but nowhere else have such a problem. So I think it could be a modem software problem. I think it could be a well known problem and there is a ready solution for it.
Would you please help us to solve this problem?
Is there any more new modem main software for this modem model?
May be any ideas?
Is it possible to update software on modem if it stops responding?
Is it possible to update software on modem via RS232 if it still responding?
SY, WR
SwD.

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