Current patch is at http://dl.dropbox.com/u/19663978/ZS_nb_qos_b14_a.tar.gz
There is an issue with it if all links go down. I’m working on that. But the basic load balancing it should work better with the patch than with the stock configuration. Instructions for installation are in the .tar.gz file.
For SIP, you should probably also make sure the SIP helper module for iptables is installed. I have the following in my Pre-Boot script:
And you should have your firewall set to allow “related” as well as “established” connections. Between these two items, the Linux routing stack in ZS will sniff out the ports it needs to open allow for media transport from the SIP dialog.