Panasonic GD76 as a GPRS modem under Linux

author: Giuseppe Rota **at**

Here i'm describing how to use the Panasonic EB-GD76 cell phone under linux as a GPRS modem.
Tests have been made under a Linux RedHat 9.0. The connection has to be made via pppd, so i will describe 2 approches. The first is with Kppp, a grafical frontend for pppd, the point-to-point protocol daemon. The second approach is for those who wish to use only pppd.


You have to know which particular device-file correspond to a phisical serial port: normally the first serial port is accessed under Linux with the device file /dev/ttyS0, but if you plugged the data cable in your second phisical port, you may nedd to access the serial port trough the device file /dev/ttyS1.

kppp initial image with a pre-existent account

new gprs account

Now click on the button. "specify the options for kppp..." (well, i guess :) and add the option noipdefault as shown in the next screenshot.

noipdefault option for the pppd

Click on OK twice and return to the main configuration window for kppp.
Click on the device tab and choose /dev/ttyS0 (or /dev/ttyS1 if that's the case, as mentioned before) and the speed at 115200 bps. Now click OK.
Re-click Setup anche choose the Modem tab. try to query the modem in order to obtain the following answer

Kppp queries succesfully our GD76

Ok, now kppp succesfully communicates with our GD76. Click close.
Now click on modem commands.
We have to fill the initialization String # 2 as specified in the next screnshoot:

AT commands

But remember that the third parameter of this AT command identifies the so called "apn" (access point network, i think) that in my case is "". Click OK twice to return to the main kppp window.
Insert something (it is not important) in the login and password fields. (i've chosen pap/chap so i have to specify a login+passw, but those will be ignored by the isp server)
Click ok to try the connection. If everything is ok now you should see on your cell-lcd the connection attempt and finally a established connection.
If something is wrong see the troubleshooting section.


pppd script file

Kppp is "only" :) a interface for pppd. (a bit more, i guess). Here i've prepared a raw howto for a pppd script.
The solution described here is working but may not be optimized for the security. See the man page for pppd for fixing it.
# client server secret IP addresses
fake_but_needed * fake_but_needed *

then you have to create 2 option-files. 1 is needed for pppd, the other one is needed by the chat program invoched by pppd.
I've named them ~/xpppd and ~/xchat
The options nomagic, kdebug, nodetach, debug should be optionals, so you can eliminate them for pppd, commentig them with a hash #.


I've seen that the tailer ",,0,0" here is obligatory.
The string ATM1L1 OK in the middle of the file is optional.

Here's how to run everything (as root on my linuxbox)

pppd ttyS0 115200 file ~/xpppd

Optional Enhancements

If everything works you may want to copy you xpppd and xchat files under
and, after some pathes fixing in the scripts, you may use the command

pppd ttyS0 115200 call xpppd

eventually you can give xpppd a more appropriate name, :) and add the ttyS0 and 115200 options into it.


Once again look out for ttyS0 or ttyS1, and insert your corret apn.
You may need, as before, to switch off and then again on your cell, or to use the ATZ Hayes command with the miniterm included in kppp.

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