TriPro Binaural 4 Pin RJ9 Telephone Headset for Landline Phones;

Description:

Only compatible with RJ9 Port call center corded telephone devices. This headset model offers a substantial increase in comfort and productivity over a handset. The most cost-effective headset solution.

Specification:
150ohms speaker, to ensure the perfect voice quality
Microphone type: electret condenser microphone(ECM)
Microphone sensitivity: 40db±3db
Microphone voltage: 2.0v
Receiver impedance: 150±10 ohm

Package Included: 
1 x 4-Pin RJ9 Crystal Binaural Headset
1 x Headset Adapter

How to use:

1, Plug the adapter (the headset comes with it) into the phone RJ9 port, then plug the headset into the adapter.
2, There is a line sequence switch on the adapter(it has the numbers 1 - 8).
3, Make sure to try each of the 8 "Channels" until you find the one where you can hear them and they can hear you.

Note: 

1, Only compatible with the most headset-ready landline telephones or devices that support 4 pin rj9 plug headset.
2, this headset just can be compatible with professional call center phone, may not be compatible with the cordless phone, please make sure the port before ordering.
3, use the headset with adapter, can be compatible more different call center phones. the adapter has 8 modes, try to test every mode on your device.
4, this headset just can be compatible with cord phone, not for the cordless phone.