Just got it working on Linux-2.6.25-rc3. You just have to enable the following in the kernel
[*] USB support --->
<*> OHCI HCD support
<M> USB Modem (CDC ACM) support
The PC300 modem will be detected as a USB modem after you loaded the PCMCIA modules.
Next, in your ppp chat script, you'll have to power-on the device before registration. To do this, send (AT+CFUN=1) to switch on the RF circuit. If you need to roam, you need to manually select the new carrier with (AT+COPS=1,0,"your telco's id"). To register to the network, I send in (AT+CREG=2) so that you'll see the network progress. Be patient, it may take more than 30 seconds before you get the OK after you send in (AT+COPS=0) the first time.
I've tested it roaming overseas and it works.
To see which network you're connecting to, send (AT+COPS?).
That's all I managed to dig around. I got the above AT commands from this link ...
http://developer.sonyericsson.com/site/global/docstools/misc/p_misc.jsp
Developers' Guidelines - AT Commands (5.50 MB)
dg_atcmd_feb_08.zip
I hope after this, someone will be able to share further findings.
Enjoy using it in Linux!
Jeff.
Share experience of connection Sony Ericson PC300 HSDPA in Open SUSE 10.3.
