By hearing their voice?

[The spoken directions he was instructed in how to use come to mind.]

That sounds like it'd be a lot less trouble for a longer talk with someone, but it'd be easier for us to just speak face-to-face.

[Hearing disembodied voices is still a bit unsettling, even if helpful in some cases. Plus, it's not like he expects that he's going to have too long of a chat on the device with anybody else too soon.

Perhaps only if he gets really lonely.]