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Please supply output of lspci for the modem. There's a good chance I know how to make this work - but the manufacturer's designation is no use since they are always misleading. (Many times the same modem is given different names. Nobody can keep track of it all.)
Chances are this is a winmodem, these do not normally work in linux. However, it is possible to get them going with some effort.
My generic advise is as follows:
1. for dialup - use an external, serial, modem. These are 100% supported out of the box and cheap second hand. They also give better performance that internal modems.
2. visit
www.linmodems.org - get and use the scanmodem tool, post it's output here for advise.
3. upgrade to ethernet based broadband