English as a second language; ESL; TESOL ; Norm of interaction; Regel (pragm.) ; Rule (pragm.) ; Interactional norm ; E-Mail; Voice mail; Chat; Computer-mediated communication ; Ingroup communication ; Mobile radio; Mobilfunk; Walkie-talkie; Voice over IP; IP-Telefonie; Telephone (language behavior) ; Metalinguistic awareness; Phonologische Bewusstheit; Phonological awareness; Focus on form (language teaching) ; Sprachbewusstsein; Linguistic awareness ; Second language acquisition (pragm.) ; Zweitspracherwerb (pragm.) ; Interactionist hypothesis (second language acquisition) ; Conversational analysis (second language acquisition)