Are you using labeling and social praise to make the contingency between desired behavior and reinforcing consequence clear to the student?
What are some reinforcing consequences you can deliver either immediately following the desired behavior or following a practice session– things that this particular student enjoys, wants, seeks out, etc.?
There are many options for integrating reinforcers that fit naturally with the types of communication being targeted. When learning emailing, the student may enjoy free-time on the internet; when learning phone calling, perhaps he receives time to play a game or use apps on a smartphone. In general, remember to use reinforcers that are valued by the student, such as alone time, reading a book, or discussing a favorite topic with you for a set amount of time.
What other reinforcing consequences can you arrange that are more naturally or intrinsically connected to this targeted behavior?