I am a telecom radio specialist, I contacted one of my colleague of core domain who looks after the HLR/HSS for the issue. He checked and found that carrier(Airtel) has blacklisted the device, the reason he dont know, and after resetting the my imsi profile on the HSS, my smartwatch able to register to network and started working smootly.
In case of general user, better contact your carrier customer care and ask to check the issue. However it is callenging to raise the case to carrier as most of customer cares guys are non technical and they try to give lame excuses and put the issue on the device.Taking the issue to the right person is most important.
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