Multiparty calls in a Philips Sopho PBX

Do like this when you wish to make a multiparty call with a Konftel 200 or 100: 

* Call the first participant. Wait for an    answer. * Press R*3 and wait for a new dial tone     (in some PBX's there will be no tone). * Call the second participant. Wait for    an answer. * Press R and all three can now participate    in the call.