I have a UC320W running with a mixture of SPA509G and SPA504G phones. When we follow the procedure for picking up a call it seems to work ok, i.e:
Highlight the call and press "Dial"
However our users were trying to use the directory like so:
Press "Dir" to find the appropriate extension
Press "Dial" to select the appropriate extension
Then the hope would be to highlight the call and press "Dial"
However pressing "Dir" and selecting the dial seems to just make a new call to the extension and cancels the "Pickup". I would therefore suggest that either Cisco allow the above procedure to work, or make the "Dir" soft key not available after you have selected "Pickup" as it seems pointless to show a key that does not work.