PhoneLoginIdentifier: {
    country: string;
    phone: string;
    type: "m.id.phone";
}

A client can identify a user using a phone number associated with the user’s account, where the phone number was previously associated using the /account/3pid API. The phone number can be passed in as entered by the user; the homeserver will be responsible for canonicalising it. If the client wishes to canonicalise the phone number, then it can use the m.id.thirdparty identifier type with a medium of msisdn instead.

The country is the two-letter uppercase ISO-3166-1 alpha-2 country code that the number in phone should be parsed as if it were dialled from.