diff --git a/lib/biju/modem.rb b/lib/biju/modem.rb
index f72ccbe..18353bd 100644
--- a/lib/biju/modem.rb
+++ b/lib/biju/modem.rb
@@ -3,6 +3,11 @@ require_relative 'sms'
 
 module Biju
   class Modem
+
+    # Receives a hash of options where :port is mandatory
+    #
+    #   Biju::Modem.new(:port => '/dev/ttyUSB0')
+    #
     def initialize(options={})
       raise Exception.new("Port is required") unless options[:port]
       @connection = connection(options)
@@ -10,15 +15,14 @@ module Biju
       cmd("AT+CMGF=1")
     end
 
-    def connection(options)
-      port = options.delete(:port)
-      SerialPort.new(port, default_options.merge!(options))
-    end
-
+    # Close the serial port connection.
     def close
       @connection.close
     end
 
+    # Returns an Array of Sms if there is messages,
+    # if not other way return nil
+    #
     def messages
       sms = cmd("AT+CMGL=\"ALL\"")
       msgs = sms.scan(/\+CMGL\:\s*?(\d+)\,.*?\,\"(.+?)\"\,.*?\,\"(.+?)\".*?\n(.*)/)
@@ -27,6 +31,12 @@ module Biju
     end
 
     private
+    def connection(options)
+      port = options.delete(:port)
+      SerialPort.new(port, default_options.merge!(options))
+    end
+
+    # private method that generate default values for serial port connection
     def default_options
       { :baud => 9600, :data_bits => 8, :stop_bits => 1, :parity => SerialPort::NONE }
     end