I got a couple of WiFi VoIP phone to test with.  The Linksys WIP330 and the DLink DPH-540.  Both phones are a pain to set up, and they are not ready for prime time.  However, for someone that travels and wants to stay connected, they still seem to be the only available option.  For the record: I had much better luck with the DLink DHP-540.

In order to get the phones running, some troubl shooting was necessery with the VOIP provider.  To inspect the VOIP packets, I had to use deep inspection with tcpdump.  Here is how:

tcpdump -nnvvXSs 1514 -i sis0 host xxx.xxx.xxx.xxx

You need to replace “sis0” with the interface on which your VOIP packets are going through.  Beware, this will generate a lot of output.