I have a Huawei E220 USB 3G modem setup on CentOS 5 (2.6.18) that works fine. On startup pppd launches a dial on demand script and it works great. It uses /dev/ttyUSB0 and /dev/ttyUSB1

I'm now trying to add a USB GPS receiver. If I plug it in post boot its picked up and added as /dev/ttyUSB2. I can then run gpsd and it also works a treat.

My problem is on boot, if I have both the 3G modem and the GPS receiver plugged in, the GPS receiver is added before the 3G modem and therefore grabs ttyUSB0. Not a problem I thought, I'll just tell the 3G modem to use ttyUSB1 and ttyUSB2 and the GPS reciever can stay on ttyUSB0. This is where the trouble started, after the GPS receiver grabs ttyUSB0, devices ttyUSB1 amd ttyUSB2 are never created for the 3G modem.

If I boot with the GPS receiver unplugged, then plug it in post boot, everything works fine. I'm trying to get to a point where I can boot successfully with both 3G modem and GPS receiver plugged in.

Is it possible to force the GPS receiver to use ttyUSB2 therefore hopefully allowing the 3G modem to get the device it wants?

Thanks in advance...