SIE Key for ACD Groups Description Any Multiline Terminal can have SIE keys for ACD Groups. When a call comes into a covered ACD Group, the SIE key will ring immediately, ring after a delay or just flash (depending on system programming and user-set options). The Multiline Terminal user can answer the call by just lifting the handset and pressing the SIE key. ACD SIE keys help maximize ACD service during high traffic periods or when agents are unavailable. The covering extension does not have to be a member of the ACD Group. In addition, an extension can have SIE keys for as many ACD Groups as it has available programmable keys. An ACD Group SIE key also allows for one-button Transfer to an ACD Group.