Our household was with which is now BSNL right from when it was Bengal and then Calcutta Telephones from late 1930's when I was not born. I still have my first BSNL line which never went down till late 1960's. after which the service nose dived specially after they replaced the well laid underground phone cable during British era with a slipshod low depth unprotected cable to my house. Our wiring both phone and CESC are totally concealed. Unfortunately the new cable got "soaked" and shorted" during water logging, and the line was out for a long time. I enquired through internal sources that a new cable has been indented for replacement and procured but was never installed!!! Where did the money go??? After infinite number of complains i was reconnected with an ugly overhead wire thin like a standard sewing thread which broke every time there was a high wind.
In spite of all this first I started to use internet through Dial Up connection of BSNL and then when they first introduced Broad Band in my locality, I was the 2nd customer who took it, since there was no other such service provider in my area. For the first year it was OK. Then the real fun started, every day there was outage, complains were useless, repeated complains invited abusive response from the ladies manning the help line - it came to a head when I told a lady I shall complain against her rude behavior, she responded "Go ahead and complain to our Chairman, I don't care.."!! Luckily the very next day Airtell who were putting underground cables and junction boxes for some time using modern machinery, better quality of cable and protective casing, approached me for a connection which I took at once. This was 9 years ago. For six months I kept both the connections connected to my two computers for comparison and found Airtel was infinitely better, rock stable, higher speed and prompt attention to any complain. I left BSNL in disgust, handing them back their handset etc. Now I know millions of subscribers of BSNL have done likewise.
------- Edited on 2016-10-06 -------
I was one of the very first customers for BSNL Broadband service in my area since we had BSNL land line connection from before I was born and when it was Bengal Telephones, then Calcutta Telephones with manual exchanges later on became BSNL.
Initially the broad band service was OK. But gradually it sunk to a so disgusting level, I took an Airtel land phone cum broad band connection and kept them both together for 6 months. I found Airtel service vastly superior than BSNL in every way so I left BSNL broadband service but kept the land phone connection just because of emotional reasons. Millions of customers have parted with BSNL and moved over to other service provider for their disgusting work culture.