what is the name of this Features?

[hmd810]

hello
i have seen a Feature in mx-one and dont know its name and how to enable or disable it.
the Features:
when two persons are talking together on the phone if third phone rings one of them and presses number 4 can make a conference with them without any permission.
can anybody help me?

 

[BlAle]

Hi!
This is Intrusion.
EXCCS:CAT=1,SERV=0015110700,TRAF=01151515,ROC=000001,CDIV=010131000;