You said
"i tried to search something in
www.linmodems.org but i didn't find anything"
Well that because you probably do not know what you are looking for. Yes I know they do not make it easy for a nwebie and expect you to become an instant geek overnight (because as Geeks they find it easy and have forgotten (or dont know) how to write out in full complete instructions - they think "I did it the hard way so every body eiles has to also" typical of the so called expert attitude ?)
Anyhow I am not an expert or a command line freek myself, so here are a few pointers that may help you ?
(1) If you are certain you have a so called Winmodem with Lucent Apollo (ISA) and Mars (PCI) chipsets - then go here:-
http://www.heby.de/ltmodem
This site has the SOURCE and installable binarys for Debian, Redhat, Mandrake, SuSE and Connectiva.
Get a binary for your distribution (RH) I went to the Canadian site.
Then go into the directory of "8.26a9" and the IMPORTANT thing to know is that you MUST get a package that has in its name EXACTLY the same kernel number as to what your operating system has. If you download the wrong one IT WILL NOT WORK
Example 2.4.18 and 2.4.20 are kernel numbers (I think 2.4.20 = RH9 - BUT - do check it on your machine as I am using Mandrake 9.1 = 2.4.21)
Then as ROOT you should be able to install the RPM and that will more than likely work right away as it creates a new device for you and also symlinks the device /dev/modem to it for you.
(2) If you do not have one of the above so called Winmodems, you must determin what sort of Winmodem you have ? There are quite a few diferent types, so check out this page:-
http://linmodems.technion.ac.il/
Get "the scanModem utility" and use it to find out what sort of modem you have ? (you will have to use the command line to manually un gzip (un gz) an then as ROOT run the file) Armed with the information that scanModem shows you go on with (3)
(3) Go to the Linmodem support RESOURCES page
http://linmodems.technion.ac.il/resources.html
Now with a bit of luck you will be able to find exacly the same type of internal or onboard modem that "scanModem" reported that you have listed on this page. It is more than likely it will come as a xxxxx.tar.gz or xxxxx.tar.bz file so as ROOT you will have to unpack and compile it your self. There is usally a README or INSTALL file in the archive that will tell you how to do it ?
Finaly: I have a Linux un-suported Laptop with a AC'97 AMR softmodem onboard, and managed to get it working from the links on the Resources page. So I hope you have better luck now ? Especially as I have showed you where exactly to look ? All the links above can be found from the linmodems.org site if you know what you are looking for !