It's frustrating, but there is not much you can "do" to make a child talk.
I am sure you are already talking him through things, and pointing out the names of objects, etc. Just keep that up. Encourage him to use his words (even if they aren't there yet). And I don't like when kids use grunts, etc. So I always say "No unh-unh's". I will try not to respond to the sounds unless necessary. Can/will he point? Does he seem to understand you?
There are many kids that don't seem to have any language, and then *poof* you can't get them to stop!! (I had one, LoL)