Despite not having 4G, BSNL has increased it's mobile customer base.

In 2016-17, BSNL's subscriber share was 8.6 per cent, which significantly went up to 9.4 per cent in 2017-18. By the end of 2018-19, it had again grown and reached 9.9 per cent and in 2019-20 it had crossed the 10 per cent, to touch 10.3 per cent. However, by 2020-21 (as on March 21, 2021), it had slightly come down to stand at 10.03 per cent, according to the Ministry's data. 

[ Courtesy: NDTV. com dt. 23-08-2021]