3Com 3C10402B Administrator's Manual page 151

Contention
The system groups audio devices, such as voice mail ports, into a pool or
extension list in the dial plan. It uses this extension list or pool for delayed
announcements. The system selects an idle device from this list to play a
delayed announcement. The number of devices in this pool is based on
usage, and you can add or remove devices to suit the call volume.
On a system with NBX Voice Messaging, you can reserve NBX Voice Mail
ports for Delayed Announcements to prevent Auto Attendant or voice
mail applications from using the ports.
1 Create a new extension list and add the ports that you want to reserve
(click Dial Plan > Extension List, and then click Add).
2 Delete those ports, which you added to the new extension list, from the
default voice mail extension list (click Dial Plan > Extension List, and then
click *0003).
3 Edit the dial plan to include the new extension list (click Dial Plan >
Configure, and then click the Modify tab).
4 Configure the appropriate ACD group to use the new extension list for
Delayed Announcements:
a Click Call Distribution Groups > ACD Groups.
b Click the ACD group's extension.
c Click the Announcements tab.
d From the Select a port to play announcements drop-down list, select
the new extension list.
The ports in the new extension list are now reserved and available
exclusively for Delayed Announcements.
On a busy system, there can be an additional delay in the playing of an
announcement. This condition can occur if all the audio resources (system
voice mail ports) from the Delayed Announcement Audio Pool are in use.
If this delay occurs, the scheduled announcement must queue up for an
audio resource to become available before it can be played to the caller.
During that time, the caller either hears ring-back (when the system
initially routes the call to the ACD Group for the initial announcement or
greeting) or Music-On-Hold (if the caller has already heard a
announcement, or the call is the result of a transfer or forward
operation).
Using ACD 151