Given that this is a app for tracking, it is not safe to assume that every single person being added will have a phone number belonging to the same country code, in this case Singapore, hence country codes should be allowed in the phone number field.
Given that this is a app for tracking, it is not safe to assume that every single person being added will have a phone number belonging to the same country code, in this case Singapore, hence country codes should be allowed in the phone number field.