sorry, I forgot to paste in the settings in the dial plan
 
<extension name="valet_park">
      <condition field="destination_number" expression="^(park\+\d)$">    
  <action application="answer"/>
  <action application="valet_park" data="my_lot@myhome.pbx2net.ca  $1"/>
      </condition>
    </extension>
 
I use park+{slot} to park calls using keys on snom and grandstream phones.   The busy lamp field lights but goes out shortly after, about 5 seconds.  However, the call is still on hold and can be picked up by pressing the illuminated light.  When I do a sip trace, there is a notify message saying the park+{slot} has been terminated.
 
Any ideals.  Incidentally, all other BLF's work prefectly.
 
Darcy Primrose