EHS Reset goes like this:
1) Disconnect power cable
2) Disconnect the TEL jack from the base, 2nd jack from the right.
3) Disconnect the AUX jack from the base, this is the largest jack in the middle.
4) If there is a HEADSET jack plugged in on the phone, disconnect the HEADSET jack from the telephone.
5) If there is a 2nd jack plugged in on the telephone, disconnect the *other* jack from the telephone. Polycom = 5-pin, Cisco = AUX jack, Yealink & Snom = EXT, Aastra = Expansion Module, Panasonic = EHS Port.
THEN, reverse the process above to plug it back in (go from steps 5 to 1), plugging the power in last.
This should work most of the time for Leitner EHS resets!
NOTE: Most Leitner EHS cables are a 2-cable set up. The TEL jack usually goes to the HEADSET jack of the phone. The AUX jack in the headset base usually goes to the 2nd jack in the phone (AUX, EXT, 5-pin, etc.). So instead of a y-cable, you will often have 2 separate cables.
The more you know!