Bsnl stands for Bharat sanchar nigam limited .it is a government approved mobile operator. I am using bsnl sim in last 2 years as 2nd sim slot. Every where the signals are come to my mobile.
Mobile data is so good but data charged are high in bsnl.In my area bsnl exchange office is there. If any problems in my sum they will clear all problems. This is very huge plus to me