Skip to content

Configuring Polycom 321 IP Phones With a Plantronics CS510 Wireless Headset

Tags: hardware, voip • Categories: Uncategorized

Table of Contents

98% of my work is software engineering and web development but sometimes I get pulled into troubleshooting random internal IT issues.

One of these was building a small business phone system. Recently it was setting up a wireless headset for the Polycom 321 IP phones.

Sounds easy, right? Nope. VOIP systems are not well documented and seem to suffering the same fate as router hardware. All the innovation in the VOIP is in the cloud, on the hardware side there is a lot of progress to be made.

So, for all those who just need to get their wireless headset to work:


  • CS510 – The wireless headset
  • EHS APP-51 – The adaptor Plantronics adaptor for the Polycom phone. Yes, that’s right, the expensive wireless headset doesn’t come with a adaptor needed to make the headset work.
  • RJ22 to Male 2.5mm – This connects the APP-51 adaptor to the IP 321 2.5mm headphone jack. This is only needed for some lower-end Polycom IP phone models. Some of the more advanced Polycom models, like the SoundPoint IP 650 don’t need this adaptor.


Plantronic Headset

For Plantronics headsets, change the coarse receive level to 3 and the transmit level to B on the headset base unit. Refer to the Universal EHS Adapter Getting Started guide packed in the headset box for more details.

Polycom Phone

I swapped a couple emails with Plantronics support before I found this piece of information:

Phone must be running SIP application 3.1 or higher and BootROM 4.1.0 or later.

Specify whether or not the electronic hookswitch is enabled and what type of headset (attribute up.analogHeadsetOption set to 2)
is attached by changing the phone1.cfg in the boot server. If this is not setup the call will hang up in 30 seconds