OK This is not about airtel or Beetel 220bx. but another crappy from BSNL Dare Global DB 108. I have this one with all the probs heats up too much, frequent ADSL link loses u name it. So I was thinking about a firmware update but found none. So I decided OK I'm gonna lose money anyway buying new lets open this thing up and look for chipset and may be I can find similar modems around. And it turned out to be Broadcom 6338. which made me search for same around and I downloaded it from the link Torch gave.
I tftp-ed to my modem connected on my LAN port and sended the .img file in.
waited for five mins. and voila it was working and working nice for last 24hrs or so with some minor hickups.. mostly I believe since I'm 4-5 kms away from exchange.
Hope this helps some...
STEPS
1. DOWNLOAD & UNZIP IMAGE file to HDD
2. rename it to 1.img or something short for ease of use(dont want type 20 letter)
3. goto Start Menu -> Run
4. Type cmd
5. Change Directory to where u stored image (i put in c:\ again for easy access)
6. Make sure ur modem is connected to ur PC's LAN/Ethernet port
7. type tftp -i IPADDRESSOFMODEM PUT 1.img
8. wait 5-10 mins . switch off and switch on router/modem
PS: my old password for the router was there if its not working try using default password
@Torch thanks for the file
Thanks to all