Hi
i am a nub on linux. i have installed RHEL 5 on my pc with dual boot on
it.
Other os is windows xp sp2 and my motorola l2 works well on xp as a ubs
modem. but i am not able to use it on RHEL 5. i am using GPRS connection
for having internet. please help me. I'll be so thank full.

Open Yast Control Center >> Network Devices >> Modem

Is your Modem detected there??
If yes then:
Select your modem & Click 'Edit' Button.

If you are using Airtel GPRS then do the following settings:

Dial Mode: Tone Dialing
Special Settings: Uncheck all
Click Next >>

Select 'Custom Providers'
Click 'New'

Provider Name: Airtel
Phone No: *99***1#
Username: a (Cannot be blank, so choose any)
Password: (Leave Blank)
Uncheck 'Always ask for Password'
Click Next >>

Check 'Modify DNS when Connected'
Check 'Automatically Retrieve DNS'
Idle Time Out: 0

Click Next >> & then Click Finish

Then download & install 'kinternet'. Its an awesome tool.
Now in your mobile: Tools >> Settings >> Connection >> Packet Data.
Set access point to: airtelgprs.com

Now use kinternet to dialup to internet

Let me know when done