Having had some line troubles recently, I was looking around and found two things: a NetGear 834G modem/router which does not drop the link when Airtel's Beetel modem does, and RouterStats software.

They do say (please google for their site, I never remember if I can post links here*) that this is not plug-and-play software, but, for Netgear 834 it needs little else than your admin login and password. With other routers might take quite a lot of work, but if you want to monitor detailed stats from your router and to be able to see them in both tabular and graph format, it could be worth it. It also gives a telnet screen to the 834.

For instance, how long, without this, would it have taken me to discover that my SNR drops to zero for a few seconds every five minutes! I might never have caught that.

It is free, and it does what it says on the box. What could be better? This! It works, using Wine, with Linux

* RouterStats