AASTRA 4420 IP Basic (SIP) for MX-ONE User Guide - Manual (Page 50)

Other Useful Features
Dialog 4420 IP Basic 50
Night Service
When the exchange is in Night Service mode, all your incoming
calls to the operator are transferred to a selected extension or
group of extensions. The exchange has two different Night Service
modes:
Common Night Service
All incoming calls to the operator are transferred to one specific
extension. Answer the call in the normal way.
Individual Night Service
Selected external calls to the operator are transferred to one
specific extension. Answer the call in the normal way.
Malicious Call Tracing
When a malicious call is received a signal can be sent to the
switched telephone network (PSTN) before a call is disconnected.
If the calling subscriber clears the call, the external line can be held
for a limited period of time to invoke the malicious call tracing
(MCT).
Order Ô
Line/Hold Put the call on hold by pressing. *39#
Dial.
If the request is successful, an acknowledge tone is heard. If the
request fails, a reject tone is heard.