PranavNair_1BvuooHlx1 Your issue may be with JIO; not the device. My mum and I ported our numbers from Airtel/Vodafone to JIO 3 months ago. Both our handsets (Samsung) were bought outside India. We had no problems while under Airtel/Vodafone. But under JIO, we were unable to make/receive calls/SMS. I called JIO Customer Care regarding this, and their response was our phones were “from foreign”. This was not mentioned (or checked) by the JIO sales rep, despite him holding/checking both our phones during the porting process.
It’s been 8 weeks since you posted, and you may well have found a resolution by now.
If not, I would suggest trying a relative’s/friend’s non-JIO 5G SIM card with your Nothing phone, to confirm if it is an issue with JIO or your phone. If Airtel/Vodafone works, you have your answer. If not, it could be an issue with your phone (assuming all network settings are applied correctly).