AskKaka lists the STD code of Mumbai that is 022. Mumbai is a part of Maharashtra and the ISO code of Maharashtra state is MH.
Mumbai STD code aka subscriber trunk dialing code is 022 which is mentioned above on this page of AskKaka. We are great resource of finding Mumbai std code of Maharashtra (MH).
Useful Info :-
Please take a note that if you are in India and dialing a landline number of Mumbai then you will have to dial STD code 022 as a prefix followed by the phone number of a landline user and if you are calling Mumbai's phone number from a foreign country then you need to add +91 (the country code) followed by 22, e.g. +9122 (no need to add "0" as prefix) followed by the landline phone number.
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