EHS36 wireless adapter plus Plantronics cs5200

[vt1]

Just purchased EHS36 wireless adapter to use with the Plantronics CS520 wireless headset on one of the Yealink T26p phone.

Follow the EHS36 User guide instructions related to Plantronics wireless headset, it fails to work.

When inbound call to the T26p phone, it rings but on the Platronics wireless headset, I hear 3 short beeps instead of regular ring tone. Upon pressing the answering button on the Plantronics, I can't hear the caller.

I noticed the headset light LED on steady green and the T26p screen displays "Talking" status but I don't hear any voice. When I press the answering button again on the Plantronics to hang up, the phone screen does change to normal idle state.

I also check the mute button and maximize the volume on the Plantronics headset of no result. Neither the caller nor me can hear each other.

Performed isolate tested on the Plantronics CS520 itself works fine.

Thanks in advance!