How to Set a Preferred Contact Method for Contacts in iOS 10
 

If you’re a fan of organizing your contacts list–like, say ditching your duplicates or grouping contacts for a cleaner list–you’ll be happy to know that iOS 10 now lets you change the default action on those blue quick connect buttons on a contact’s page.

http://www.howtogeek.com/272011/how-...cts-in-ios-10/