Using the Creative USB Modem with Linux

Introduction

The Creative Modem Blaster USB DE5670 is a capable external modem that works well with all the versions of GNU/linux that I've used. However, it takes some work configuring the OS to recognise the modem before it can be made available for normal users. When using the 2.4 series kernels, I just made the modem device nodes once by hand, but with 2.6, comes the dynamic udev filesystem so I tried to add relevant entries for automatic device creation.

Using the Creative Modem Blaster with 2.4 series kernels

As root, the superuser, type the following commands, 
mknod /dev/ttyACM0 c 166 0
ln -s /dev/ttyACM0 /dev/modem
modprobe cdc-acm
Then, as a normal user, you should be ready to configure and use kppp where you specify that your modem is available at /dev/modem

Using the Creative Modem Blaster with Mandrake 10.2 Limited Edition 2005

Not really knowing what I should be doing, I tried a few approaches, found an imperfect solution and may have done some work unecessarily. The details are shown below. 
echo 'ln -sf ttyACM0 /dev/modem' >> /etc/udev/conf.d/modem.conf
echo 'KERNEL="ttyACM0", SYMLINK="modem"' >> /etc/udev/rules.d/modem.rules
and added the USB device information to /lib/modules/2.6.11-6mdk/modules.usbmap 
cdc-acm              0x0003      0x1690   0x0101    0x0000       0x0000       0x02         0x00            0x00            0x00            0x00               0x00               0x0
However, this is not a permanent or approved solution because this usbmap file is overwritten each time that kernel module dependencies are regenerated with the "depmod" command. I don't know the correct place to store the USB device info so it is regenerated by depmod - somewhere in the kernel source ?

The situation is also puzzling because even before the usbmap file was updated, and when usbview listed the modem in red (unknown), there was still one command where the modem was listed as being of the correct communication type "cdc-acm" but this information wasn't being used anywhere as far as I could tell ?

usbmodules --device /proc/bus/usb/002/008
cdc-acm

USB Identification Data

This is what usbview shows about my modem: 
Creative Modem Blaster USB DE5670
Manufacturer: Creative
Speed: 12Mb/s (full)
USB Version:  1.00
Device Class: 02(comm.)
Device Subclass: 00
Device Protocol: 00
Maximum Default Endpoint Size: 8
Number of Configurations: 2
Vendor Id: 1690
Product Id: 0101
Revision Number:  1.00
Maybe I should set up a usermap file in /etc/hotplug/usb/ Just like what was done here for patching and playing with Velleman K8055experimental interface board. Also availabel from Maplin in Britain.

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