Airtel 4g sim (Delhi) all of a sudden stopped working after rebooting blackberry passport

Hi
I have ported from bangalore Airtel to delhi Airtel but after two days of porting in my sim is not working. It's showing emergency calls only but that sim is working on another phone. Is there any compatibility issue or the software issue as the old sim when I have inserted is able to recognize in another mobile.
But I mobile network it's showing Airtel. Do I need to change the sim to 3g as its a 4g sim. Please help

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I am attaching the snapshots for a better understanding

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Thank god luckily it started working after putting it into 2g mode.

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Seems there is network issue in delhi as it was not at all working in any other modes before.

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Is Airtel Zambia also affiliated here?

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