Callers transfered to queue can talk together

My system have 2 queues, one that is used for all incoming calls, and the secretary answers the call, and transfers them to another queue.
Sometimes in this queue it is possible for the queued calls to talk together as in a meetingroom.

When the calls in the queues dials the agents it’s with this cmd Dial(sipuser,rtT).

My system is Debian, an Asterisk

any help would be appriciated.