1st Phone Calls Phone 2 via Jabber.
Second phone searches for or direct dials 3rd phone
Once the 3rd party has joined the active conversation window resizes itself, the call control buttons disappear, the search for party/call number box disappears.
If you resize the box the call control buttons come back, but not the search for/call number box.
If the call is made from a group by right clicking on the group name and starting conference call this issue does not present itself.
If the call is made ad-hoc from the phone the issue does not present itself.