Pmc, we're using a WRV200 with BEFSX41's and don't have any problems, it's mainly the low-end Linksys like the BEFSR41's that have voice issues.
Definitely turn off 802.1p and diffserv/DSCP, those will cause one-way voice unless EVERYTHING between phone and LIPU supports it, and most internet routers don't. Also, make sure your LIPU is using the latest firmware, I think it's 51D. Also, turn off peer-to-peer unless all phones are on the same local network.
