Latest 3CX, latest firmware on my Yealink T46G phones. In the Phones node in 3CX, the "Phone UI" button does not work. Clicking on it does nothing. I've found that it depends on the template I'm using. I can factory reset a phone and then assign the default T46G template to it and, after all its reboots and configuring is finished, the "Phone UI" button does not work. This is with what 3CX calls a "supported" scenario: phone factory reset, using the default template. However, if I factory reset the phone and assign my older custom template to it, then that button does work and does what it's supposed to do: open the phone's UI at its IP address in another tab in the browser.