Outside compatibility adjustment by 2 pin slide switch.
Comply with most of Single-line/Multi-line telephones
Feature
Headset/Handset selection switch
Microphone polarity selection switch for exact compatibility of microphone
Mute switch for temporary call suspension.
No battery required
For simple switching between a Handset and a Headset.
Connect asper the diagram above. The Headset must be connected on the "Headset" output and the handset also on the "Handset" output. The mute button cuts off the microphone. Push the switch again to resume communication
with your caller.
Notices: This advice has been sent to the most common configuration. However, your telephone may be different require a different setting to be compatible.
To change connection setting:
1) Slide the compatibility switch located on the side of the device unit it can be properly adjusted.
2) The position of polarity switch is on the right side before factory release as below drawing. To adjust properpolarity switch, make a phone call to your friend and adjust slide switch to the left & right by turns until he can hear your voice more loudly and clearly.
Notices: If you do not properly set the polarity position, the sensitivity of headset microphone will be decreased and dead easily.
3) If you are still experiencing difficulties, the headset configuration may be incompatible with this device.