Mobile phones can be used in many ways to support second language learning both inside and outside the classroom. The document outlines 20 practical ideas for using mobile phones, focusing on developing the four skills of speaking, listening, reading and writing. Some key ideas include using the phone's notes, camera, and voice recording features to collect language samples from daily life. Free programs can help organize language samples and create flashcards for mobile study. Overall, mobile phones provide a way for students to access language materials and practice anytime, anywhere.