6310i does not support socket communication. Neither does it have the messaging api (present in devices such as the 3410). Your only route is to use a rather naff polling mechanism. Or try to hold open 2 HTTP connections - one post and one get (using chunking you can effectively send packets of data).
Correct me if I'm wrong, but holding 2 connections open won't work on all the phones- I did some tests on a 7650 and it seemed to be unable to open 2 connections simultaneously. A 6310i did however, so if you're not programming for portability, this should do the trick.