Turns out this was not the manual i was looking for. The concertmate 670 keyboard i have is a "Realistic" model made for Radio Shack and none of the diagrams on the owners manual i received matches up. HOWEVER, I must say the service Owners Manual provides was fast and efficient by being available online. The manual was in good readable condition and easily downloaded.
Actually, I was looking for this information for 3 years!...now thanks to you, the manual is on my hands and of great help, cause I understand now where I was doing wrong connections and wires...excellent, I'll be back to you if in need, thank you.
Text excerpt from page 50 (click to view)
Belt Clip
You can hang the handset on your belt or pocket using the belt clip.
To attach the belt clip
To remove the belt clip
Optional Headset
Plugging an optional headset into the handset allows a hands-free phone conversation. Please use only a Panasonic KX-TCA88 or KX-TCA90 headset. To order, call the accessories telephone number on page 2.
Connecting an optional headset to the handset
Open the headset jack cover, and connect an optional headset to the headset jack as shown below.
The illustration headset is a KX-TCA88.
H
Headset Jack
To switch to the speakerphone while using the headset: Press . To return to the headset, press .