Sim800L issue not connecting to network

Connected to Arduino Uno and powered by a separate 5v 1A supply. the module responds to AT commands but does not connect to the network (using Airtel 4G sim card).
The description in the link says that the module is 5v compatible or should i use a 4v 2A power supply with voltage divider between RX.

If your module doesnt have 4V regulator on board then you have to use 4V supply.