def get_ext_name(names_key, id_key)
      return nil unless ext_data[id_key] > 0

      res = Phonelib.phone_ext_data[names_key][ext_data[id_key]]
      return nil unless res
      res.size == 1 ? res.first : res
    end
def get_ext_name(names_key, id_key)
      return nil unless ext_data[id_key] > 0

      res = Phonelib.phone_ext_data[names_key][ext_data[id_key]]
      return nil unless res
      res.size == 1 ? res.first : res
    end
@private get name from extended phone data by keys

 ==== Attributes

 * +name_key+ - names array key from extended data hash
 * +id_key+   - parameter id key in resolved extended data for number