OK
I found a solution.
Connect the UT304R2 modem
In Internet Exlporer type in 192.168.1.1
User/Pass is admin/admin (in case you have not changed it)
Enter the telephone number and the password.
Note: Do not enter the telephone number in the format which Airtel requires
<telephone number>_dsl@airtelbroadband.co.in
Just enter the telephone number (prefix STD code 0120)
Save
Go to Tools
Go to System
Click on the Save button for "Save Settings to Local Hard Drive"
Save the committedcfg.cfg to your desktop
Open this committedcfg.cfg using notepad
Search for the telephone number
Only one result will be found
suffix the telephone number entry with
_dsl@airtelbroadband.in
Save the committedcfg.cfg
The Tools->System
For "Load Settings Local Harddrive" click on Browse
Select the committedcfg.cfg file
Click on Upload
The modem will reboot
BINGO.. Issue resolved
This is just a workaround.
I am still looking for the firmware for UT304R2.
Any suggestions?