AT&T MERLIN LEGEND System Reference Manual page 244

Features
Related Features
Assign an external alert to notify calling group members of a Calls-in-Queue
A l a r m .
Extensions -> More -> Grp Calling -> Xtnl Alert
Set the overflow threshold and designate a calling group or QCC queue to
provide overflow coverage.
Extensions -> More -> Grp Calling -> Overflow
Change the calling group typesetting to determine whether or not calling
group members are automatically logged in after a system cold start (no auto
login is the factory setting). When the calling group is used for voice
messaging systems, specify whether the type of voice messaging interface
(VMl) is integrated or generic.
Extensions -> More -> Grp Calling -> Group Type
Extension Status
Group Calling 2-195