You may be thinking about Group Call but the call doesn't come out of the speaker of the phone.
Group Call allows a user of a Meridian 1 proprietary telephone to place a
call to up to ten Directory Numbers (DNs) simultaneously by activating a
Group Call key. The called DNs must have been previously defined as
members of a group.
Each customer within the system can have up to 64 groups assigned.
Each group has up to 20 group members. Any DN in the system can be
assigned as a member of a group, and a DN can be a member of more
than one group. For Small Systems six members per group are allowed.
Each Multiple Appearance, MCR/MCN DN reduces the number of
telephone sets that can be added to a Group Call. For example, if two
telephones have the same MCR appearance of a DN, the number of
telephones in the Group Call becomes 19. That is, each appearance of a
DN counts as one member, up to a maximum of 20, of the Group Call.
Multiple Appearance, SCR/SCN DNs count as one member of a Group
Call, irrespective of its number of DN appearances.
Call
Groups are defined through Service Change in LD 18. When a group is
defined, each member of the group is assigned a member number. If
network or conference blocking is encountered, members are assigned
priorities for connection to the Group Call in the order of their group
member numbers (member 0 has the highest priority). It is recommended
that group members be assigned from different network loops to minimize
the possibility of network blocking.
The Group Call key is used to originate a Group Call to all members of
the group to which the Group Call key is assigned. The Group Call key for
a given group can appear on more than one telephone. More than one
Group Call key can be assigned to a group, but only one Group Call key
can be active for a given group at any time. A telephone with a Group Call
key need not be equipped with a Directory Number (DN) that is defined
as a group member.
Activation of a Group Call key originates a call to all assigned members of
the group. When the first member of the group answers, ringback tone
is removed and a speech path is set up between the member and the
originator of the call. As subsequent members answer, they are added to
the call. The lamp associated with the Group Call key at the originator’s
telephone flashes until all members of the group have answered the call.
If a Directory Number (DN) is actively engaged in a call and a Group
Call is originated for that DN, either the Group Call is camped on or Call
Waiting is activated for the DN and a special warning tone is provided. The
special warning tone consists of three rapid bursts of tone followed by 10
seconds of silence, then an additional three rapid bursts of tone.
An active Group Call is under complete control of the originator of the
call. If the originator goes on hook, the call is completely broken down.
Members who are taking part in a Group Call can disconnect from the call
at any time, but once disconnected, they cannot be reconnected.