Have a customer with an INT 5000 (2.1.0.13) and 550.8520 phones and Plantronic headsets (M12 and M22 bases).
One extension has a regular tick, almost like a heart beat, on the headset while idle or on a call. The tick matches the flash of the time colon on the display when idle.
Moved base to another extension and ticking followed. Replaced base and ticking went away ...for 24 hours. When it came back it was a double tick. Tried a different physical phone, still got the ticking. Switching out headset base with new one makes the ticking go away.
Changing out bases daily seems like a bad idea.
Ideas?