AASTRA 4220 Lite for BusinessPhone User Guide EN - Manual (Page 13)

13 BusinessPhone – Dialog 4220 Lite / Dialog 3210
Description
Signals
Ringing signals are emitted from the phone.
Note: The tones and ringing signals in this guide refer to the
standard system but may vary between countries.
Internal ringing signal - repeated after 4 s
External ringing signal - repeated after 4 s
Automatic Callback signal