BSNL at any place is used to be dependent on the local exchange offices attitude and proximity of your home to the local exchange.
Now it also depends on your LCO guy: If your LCO guy is good, you will most likely have a smooth overall experience, I would recommened you to consult the locals in your area about his reputation.
Ping: To judge BSNL's ping especially with regard to connection quality, measure your pings to
Google dns(ping dns.google , don't put 8.8.8.8 or 8.8.4.4) and cloudflare dns pings
Based on that you can get a fair idea of your pings to most of the servers local or international
Google pings:
Less than < 20 ms : Your pings will be reasonably good to most servers
< 25 ms : You are still lucky, some servers might be shaky but overall good
< 30 ms : Some server might be good, others be bad, you won't get best pings but won't be in the worst zone
30+ ms : Gaming might not be fun, only cache servers on BSNL/ local network might give you manageable pings
Reasoning: this is BSNL's routing as of now:
Your LAN
router/modem --> Your LCO Router --> Your Local Exchange Router --> Your City Exchange router--> THE BIG REGIONAL Router
At this BiG Regional router: BSNL handles off your packet to either Airtel or to
Tata and host Google's DNS server/Earlier it was handled to Airtel.(sometimes still do)
Also for the local caches(like NFLX OCAs), your city exchange router decides where to redirect your packets
NOTE: This advice subject to change in BSNL's routing policy.