SMS as a medium, what makes sms to be used as it is?

Please allow me to introduce myself, I'm a student in Amsterdam and my studies are "Media & Culture" combined with "Political sciences".

For my final thesis I would like to examine exactly what place SMS-messaging has whitin the whole array of communicating media such as telephone, cell phone, but also letter and the face to face spoken word.

So why is SMS used in a certain way, and why is this specific type of use of a medium a product of it's form (in this case a small one-way message, about 160 characters, sent within seconds to anyone with a cell number around the world)?

I am very interested in finding material and thoughts other people have regarding these questions.

Regards,
David de Nood

Student
Amsterdam