When using a dual sim the Iphone has a system where it automatically overwrites the default sim card to be used for calls and messages. Instead it uses a setting saved per contact that it will choose a sim based on the last call or text from/to that contact. Due to this I often use the wrong sim card. I want to use one sim for all calls and messages unless I very explicitly change that for the contact.
Can I change the "Preferred Line" setting for many or all contacts at once?