BSNL is the the king of telecom industry in india and there is not any 2nd thought about it.Also available in all over country.
The speed of ISP connection is very fast and smooth run.
BSNL broadband service is notorious in terms of reliability, no gurantee on uptime. The wimax is a life server. In normal cases the connection would not go down. If some thing goes wrong at their end, at least we can expect that it will be restored automatically.
The Customer service no is 1500. But my view the support and service is not satisfactory other than like JIO, airtel