Yes! It does work. You just need to point the extension in iSymphony to the Zulu PJSIP extension, not the primary PJSIP extension.
Inside of iSymphony admin panel:
Phone System -> Extensions. Find the Zulu extension and edit.
Change the Peer value to match the actual Zulu PJSIP extension. Example:
If your Peer value is set to: PJSIP/77228, you would change it to PJSIP/9077228
Save and now it works.