I use Airtel broadband in my home. I noticed sometime back that I could not connect to any IRC channels from my home.
Then after googling about similar problem faced by others found a solution for that.
Airtel seems block port 6667 which is usually the default port used by IRC clients.
So to connect to IRC ports other than 6667 should be used if connecting using Airtel
I use port: 7000 for connecting to my favorite IRC channels.
For example to connect to my Tamil localization channel #thamizha in freenode, i use the following command in my firefox browser (with chatzilla Plugin) address box:
I hope this tip might be useful to some of you who use Airtel internet connection in India :)