[{_id:ObjectId("666225dbe02f02db7f19465a"),lastName:"Smith",firstName:"John",middleInitial:"",email:"john.smith@corp.com",phone:[{international:"",area:"555",prefix:"555",number:"1234",ext:"",name:"work"},{international:"",area:"555",prefix:"555",number:"2345",ext:"",name:"cell"}],address:{work:{city:"New York",province:"NY",buildingName:"Empire State Building",address:"20 W 34th St.",postalCode:"10001",mailstop:"49B"}},positionId:ObjectId("666225dbe92f02db8f09465d")}]

db.collection.update({},[{"$set":{"phone":{"$map":{"input":"$phone","as":"p","in":{"$mergeObjects":["$$p",{phone:{"$concat":["(","$$p.area",") ","$$p.prefix","-","$$p.number"]}}]}}}}}],{multi:true})