ASL Holdings Limited
19/09/2005
16
Draft Copy Version 2c
1 CONNECT
Connection.
2
RING
Ringing signal detected.
3
NO CARRIER
Carrier lost or never present.
4
ERROR
Invalid Command.
6
NO DIAL TONE
No dial tone detected.
7 BUSY
Busy
signal
detected.
8
NO ANSWER
No answer from remote modem.
GPRS operation
The three main commands used to set up a GPRS call with the Delta Plus
MOBILE II GSM/GPRS modem in listening mode are as follows:
AT+Gn, where n = 0 to 9
AT+G0 - turns off GPRS mode
AT+G1-9 turns on GPRS mode and auto connects using context 1-9 then
listens for a port 23 connection.
If AT+Gn is on ( ie n = 1-9 ) then it will restart if the connection fails, also at
power up. To set contexts (n = 1-9) in the following two commands:
AT+CDGCONT = n,”IP”,"Enter access point name (APN) address here"
.
AT*ENAD = n,"GPRS","username","password",1,0
To escape from TCP/IP listening mode when a session is not connected issue
a Ctrl C.
This can take several minutes to “detach” from the network and will set
AT+G0 until +G is changed or a reset or a power cycle is invoked. This will set
the modem back into auto mode.
Firmware version 2.10 and above:
Additional GPRS watchdogs have been added to the modem in order to
negate network fail conditions, these ensure that the unit continually re-tries to
connect in GPRS mode if a call failure is detected.
Timeouts:
Typically these are –
Online GPRS inactivity timeout of 4m 16s (256 seconds) - covers failure mid
session
User exit from GPRS mode (Ctrl C) times out & GPRS restarts after 1m 42
secs unless the AT+G command is used.
Fail safe timeout restarts every 3h 37.6 minutes if unit is offline. Covers
random GPRS network failures!
Lack of Signal/Signal Quality (SQ) timeout is 45 minutes.
