USSD code *#07# nor working on iPhone XR

I am dialling USSD code *#07# on my iPhone XR , I am receiving a error message "Error performing request Unknown Error ". I have tried to i) change the phone setting e.g turing of call forwarding, ii) change the call setting switching off call forwarding etc, iii) update all downloads iv) reset network setting etc. Nothing works. All other USSD code e.g. *#06# is working.

Please help me fix this problem 

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