AT&T MERLIN LEGEND Release 2.0 System Programming Manual page 159

Programming Procedures
Hold Disconnect Interval
Use this procedure to specify the number of milliseconds before a loop-start
trunk is released when a caller on hold hangs up and abandons the call. This
can be specified as either a long interval (450 ms) or a short interval (50 ins).
The hold disconnect interval applies to loop-start trunks connected to 400, 408,
or 800 modules; it does not apply to emulated loop-start trunks (T1 facility).
NOTE:
If the disconnect interval is longer than the telephone company setting, the
line is not released when a caller on hold hangs up. Do not program a short
interval unless the local telephone company's central office is the crossbar
type.
Do not program a reliable disconnect for trunks with a short hold disconnect
interval. This can cause active calls as well as trunks on hold to be
disconnected. See "Disconnect Signaling Reliability."
For more information on Hold Interval Disconnect and Reliable and Unreliable
Disconnect, see Feature Reference.
Entering Programming
Console: Select Menu
PC/SPM: Type SPM
Exiting Without Changes
To exit from any screen without making changes, select Exit on the console or
[F5]
press on the PC before saving your entry or menu selection.
3-68 Hold Disconnect Interval
Sys Program Exit
[F1]
press any key
[F5]