8.14.3. User Interface 
- The user may either depress a key (BROADCST) or dial an access code
(BROADCST), followed by dialing a destination extension number, to initiate
a Broadcast call. A one-way connection shall immediately be established
between the user and up to 40 keysets which have a line appearance of
the dialed destination and meet the following criteria:
- The line appearance on the telephone is configured to ring.
- The station user is not busy, not off-hook, not in hands-free operation,
or is not in program mode.
- The destination is not marked for voice call protection.In default
this is on.
- The station is not restricted from terminating to that destination
(e.g. ITR Internal Traffic Restriction).
- An external dial tone shall alert the originator that the one-way connections
have been established, and that the one-way Broadcast can begin.
- The Broadcast connection shall be converted to a single two-way connection
upon any active Broadcast destination's going off hook, via the
handset only. The two-way connection shall be established between the
party that initiated the call and the first party that went off hook.
All other parties will be released from the call.
- A Speaker Call -- One-way - Broadcast call can be initiated by an
analog or digital telephone.
- When a destination party presses the speaker key, the party will
be disconnected from the Broadcast (speaker turned off). If the last
party presses the speaker key, the call will be disconnected.
- When a destination party presses a line key (either the one on which
the Broadcast is pending, or any other line key), the party will be disconnected
from the Broadcast (speaker turned off). If the last party presses a
line key, the call will be disconnected.
- The number of simultaneous Speaker Call -- One-way - Broadcasts is
10 with 40 members each.
- The destination parties receive a momentary burst of ringing and
the calling party remains on the display of the destination parties.