Here is the applescript to convert your all phone numbers on contacts that started with “0” to country code. Just replace the “+62” with your country code"

tell application "Contacts"
 repeat with aPerson in people
  set thePhones to phones of aPerson
  if thePhones is not {} then
   set errorList to {}
   repeat with aPhoneNumber in thePhones
    set theNumber to value of aPhoneNumber

    if (characters 1 thru 1 of theNumber) as string is "0" then
      set StringLength to count of characters in theNumber
      set newNumber to "+62" & (characters 2 thru StringLength of theNumber)
      #display dialog theNumber & " to " & newNumber

      set value of aPhoneNumber to newNumber
     on error
      copy name of aPerson to end of errorList
     end try
    end if
   end repeat
   if errorList is not {} then
    display dialog "Couldn't change: " & items of errorList
   end if
  end if
 end repeat
end tell