There are 3 compatibility switches:
When using this product with a computer, the only relevant parts are the volumes, the actual compatibility switch only has effect on the connection to the phone.
This adjuster actually alters the use of wiring the MX10 will use to communicate to the phone and this will hence need to match the requirements of the telephone. The standard setting is number Five and if you are having acoustic issues, it may be worth trying each number until you hear the clearest sound whilst on a call.
To get phone specific details on which setting to use, please either contact the supplier of the product, or contact Plantronics support. Please note you will need to state you are using the MX10 and you will also need to know the phone manufacturer and model.
Microphone Volume Switch
This adjuster is a simple device. Turn it clockwise to increase the microphone volume; turn it anti-clockwise to decrease.
If you are hearing yourself when you speak, this will either be because the compatibility switch is in the wrong position, or the transmit volume is set to high.
Receive / Earphone Volume Switch
This 'dial' is the big switch on the front of the product numbered 1 - 9: 1 is the lowest volume; 9 is the highest.
If you find that the caller on the other end of the phone is hearing themselves, this will either be because the compatibility switch is in the wrong position, or the receive volume is set to high. This can be tricky as you will need to find the right balance between the volume from the phone, and the amplification on the MX10, but we normally recommend using about 70% on the phone, and adjust the MX10 accordingly.
Link to: MX10
Link to: MX10 Product Information