Thanks to the help of Daniel Richman (Alien Project), the control of the Sony Ericsson T68i is easier than ever. You just hook up two wires to your arduino (GND(orange) and RX(blue)) and you can call and send textmessages. The complication was the PDU codes. Daniel has written a nice little piece of code, that you do not need to worry anymore.
You just say “send_sms(<blablabla>)” and within 1 second my iPhone started ringing that a new textmessage had arrived!
This is the cheapest AND easiest €10 solution to call or send text messages, sms, with the arduino to your phone. Cheap and easy, i like it.