Sign languages are usually the mother tongue of deaf people. The official language spoken in a given society is learned as a second language by them. The process of learning this second language is something hard and complex because deaf individuals are not able to hear sounds of any oral languages. Actually, they use such languages only through written messages. This study discusses how the use of smartphones by teen deaf students contributes to the acquisition of Portuguese as a second language, identifying how deaf individuals use smartphones to interact with other deaf and with hearing people through written Portuguese. The research was developed in a qualitative approach with five deaf participants from high school in Brazil. Data were collected through interviews and observations and showed that the use of smartphones has provided multimodal tools that enable the deaf to overcome linguistic and cultural barriers related to the use of Portuguese. Through digital devices they can learn the language with the help of translator apps, images, videos and texts, becoming more proactive and independent in the learning process.