Bsnl has plenty of high speed (4 MPBS) plans as mentioned here :
These are on the NIB - II Network. Ip addresses begin with 117.
One known problem with the high speed internet is that it gets disconnected frequently. So like Yahoo Messenger or Pidgin or Skype could go offline every 5 minutes and then connect back.
How to Fix
Here are a couple of tweaks that might fix the problem.
1. Disable all modulations except G.Dmt Enabled. This will limit the download speed to around 4.8 Mbps (4984 Kbps) and the upload speed to 207 Kbps.
But can make the connection a lot more stable.
Change the settings in the admin panel (192.168.1.1) and then restart modem.
2. Choose a LAN Ip with larger number in 4th octet like 192.168.1.100 , 192.168.1.101 , instead of 192.168.1.2 , 192.168.1.3
Not sure why it would effect the stability , but it may have some effect if multiple computers are using the same connection in a LAN.
3. Check the hardware
Make sure that the adsl line is stable - Link light stays stable. SNR Margin should be high and line attenuation should be low.
SNR Margin (Signal to Noise Ratio Margin) – You have to watch out for SNR Margin (usually in 20?s) and if it is too low you may get disconnected often.
Line Attenuation – It measures loss of signal over distance and its value in 20?s means excellent.
Meaning of various values are as follows :
A higher signal to noise ratio will result in less errors.
6bB. or below = Bad – experience intermittent synchronisation problems.
7dB-10dB. = Fair
11dB-20dB. = Good
20dB-28dB. = Excellent
29dB. or above = Outstanding
Attenuation is the loss of signal over distance. Unfortunately, dB loss is not just dependent on distance. It also depends on cable type and length of the cable, including location other connection points on the cable.
20bB. and below = Outstanding
20dB-30dB. = Excellent
30dB-40dB. = Very Good
40dB-50dB. = Good
50dB-60dB. = Poor and may experience connectivity issues
60dB. and above = Bad and will experience connectivity issues
Also check the following :
Phone line has not too much noise.
Wirings are not too old and torn
Splitter should be OK