AASTRA DT4x2 for BusinessPhone User Guide EN - Manual (Page 120)

Troubleshooting
BusinessPhone – Cordless DT412/DT422/DT432 120
Keys locked
Unlock
The key pad is
locked.
Press Menu key
followed by
*
.
No system Cannot connect to
the network, the
Cordless is not
registered or out of
range.
Contact system
administrator.
Fault / Display Probable cause Action or
comment