Microsoft India has started the roll-out of new firmware update for select Lumia devices in India. This new firmware enables 4G support in those devices allowing consumers to enjoy 4G network which has just started to spread across the country. If you received an update in the last few days, this is the update. Check under mobile data settings whether you now have 4G option in addition to 3G and 2G
The devices which are getting the update :-
Lumia 1520
Lumia 1320
Lumia 1020
Lumia 930
Lumia 925
Lumia 920
Lumia 830
Lumia 625