AASTRA DT292 for MX-ONE User Guide EN - Manual (Page 76)

Other Useful Features
DT292 76
Malicious Call Tracing
If you are disturbed by bothersome or malicious external incoming
calls, you can request number tracing from the network provider.
You can invoke tracing during or after an ongoing conversation.
The external line can be held for a limited period of time.
Order
During an ongoing conversation: »
Press.
Dial tone. *39#
Dial.
The system acknowledges with different tones whether the tracing
request was accepted or rejected.