This paper presents a study examining users' perceptions of privacy relating to mobile phone usage, and more specifically on the use of short message service (SMS) messages. The study also looks at the reasons for mobile phone ownership, and user perceptions on possibilities for added privacy with mobile messaging communication. The user study consisted of a written survey of 119 people and ten interviews. Results confirm that most respondents feel mobile phones are private and personal devices, and that SMS messages are perceived as more private than normal calls. This research found user privacy is guarded by widely accepted, unwritten rules of treating phones and messages as confidential, and there exists little need to complicate this communication medium with technical means of securing user privacy (e.g. encryption).