Mandriva not recognising Sitecom DC-009 USB modem

Q I have installed Mandriva 2007 to a Dell 5150. The Dell has no serial or parallel ports, just USB. I have a Sitecom 56k V.92 USB modem, model DC-009, but I cannot get Mandriva to connect to it. The USB keyboard and mouse work fine. I can get the cdc_acm module to load with modprobe but it does not seem to connect to a tty, although KPPP sees ttyS0 and ttyACM0 and reports 'modem busy' when I query the modem on either ttyS0 or ttyACM0. I have trawled the net to no avail, including www.linux-usb.org. The modem worked out of the box in Windows XP. These issues should surely be a thing of the past by now?

A It would appear that this modem either is not fully supported or needs some kind of firmware file. This particular modem failed to show up on a web search, but that is not too surprising. Many of these devices are made by one manufacturer and branded by another. However, all such devices need to be approved by the FCC (Federal Communications Commission) for sale in the USA, so you can find out what it really is from its FCC ID code. Type the code into the box at the bottom of www.hardwaresecrets.com/page/fcc to find out who really made your modem. Once you are in possession that information, a search of sites like www.linux-usb.org should prove a lot more fruitful. There is a further complication that has a bearing on your situation: USB modems can be problematic because they are not truly standardised, with only some of them conforming to the CDC-ACM specification. Your USB keyboard and mouse work well because they all conform to the same standards (USB HID). One way to sidestep this problem is to use a serial modem via a USB serial adapter. I have a couple of these devices, using different chipsets and both bought cheaply from eBay, and they both work very well with the majority of the serial devices I have tried (a UPS being the only exception). This way you can use any serial modem, as well as any other serial devices you may wish to use with this computer. It seems that we have managed to get rid of parallel ports and floppy disc drives, but the old serial port just won't go away.

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