quality:correction
Japan

Japan was among the first countries to adopt short messages widely, with pioneering non-GSM services including J-Phone 's SkyMail and NTT Docomo 's Short Mail. Japanese adolescents first began text messaging, because it was a cheaper form of communication than the other available forms. Thus, Japanese theorists created the selective interpersonal relationship theory, claiming that mobile phones can change social networks among young people (classified as 13- to 30-year-olds). They theorized this age group had extensive but low-quality relationships with friends, and mobile phone usage may facilitate improvement in the quality of their relationships. They concluded this age group prefers "selective interpersonal relationships in which they maintain particular, partial, but rich relations, depending on the situation". The same studies showed participants rated friendships in which they communicated face-to-face and through text messaging as being more intimate than those in which they communicated solely face-to-face. This indicates participants make new relationships with face-to-face communication at an early stage, but use text messaging to increase their contact later on. As the relationships between participants grew more intimate, the frequency of text messaging also increased. However, short messaging has been largely rendered obsolete by the prevalence of mobile Internet e-mail, which can be sent to and received from any e-mail address, mobile or otherwise. That said, while usually presented to the user simply as a uniform "mail" service (and most users are unaware of the distinction), the operators may still internally transmit the content as short messages, especially if the destination is on the same network.