> If this is not a data grab and they have perfectly good technical reasons to do this without consent, I am interested in knowing those reasons.
Not saying it isn't being used for a data grab (knowing India's lack of enforcement it probably is) but SIM and IMEI verification is now done in India now under CEIR [0][1]
If you want to trace a stolen phone, the IMEI is known by the Telco so it can be traced back.