The LCO will take new connection charge but ONT device can be the same. In my case, once I got problems with Railwire so LCO was suggesting to shift into BSNL and offering some discount. I didn't took the connection since problem was resolved from Railwire end.
The only problem i have with BSNL is their plans are not competitive compared to other private operators. I pay 200 more for what i will pay for same plan in Jio Fiber. Otherwise they are good. Even in Sunday, they come to solve my problems. It just depends on the local management. Private operators don't go to less customer areas. While BSNL came to my colony only because i applied. We were the only customer that time. Then some 5-6 more families brought their connection. They deserve some credit for that.