Are you using Plantronics (now Poly) DECT Wireless Headset such as this, and do you see headset turning off after 15 seconds to 1 minute? Most likely this can happen if Cisco Phone firmware was updated.
Hope you will find following troubleshooting tips helpful:

Cisco and Plantronics
Note: Know that your call is not dropped. So if the above issue happens in the middle of the call, then pick the handset and continue your call.
- Place headset (A) back in the Charging Base (B). Unplug the EHS cable (dual plug X) and the power (smaller and round) from the back of the charging base for the headset.
- Unplug the other end of the cable (Y) from the Cisco phone.
- Follow these steps in this exact order:
- Start with the EHS cable NOT connected to the phone or the headset charging base (B)
- Headset charting base (B) must NOT be connected to power (no lights)
- Reboot phone: unplug Cisco phone from AC power (or from Ethernet cable if no AC power), and leave it unplugged for 30 seconds and then re-connect.
- Phone will take a few minutes to come back up. Lift the handset to verify you have dial tone before proceeding to the next step.
- Connect the EHS (Y) cable into the Cisco phone.
- Connect the power supply only to the headset charging base (B) and wait until there are two green lights in the silver bar on the front.
- Connect the EHS cable (X) to the headset charging base (B)
- Press the call control button on the headset (A) 1-3 times, dial tone should be heard.
Are you still having issues? Give BTP a call at (425)649-9262, or email us at info@btpi.com.
If you are doing a big headset project, do not do yourself. Managing hundreds of headset users can be very time consuming. Since 1991, BTP has been helping with headsets (live troubleshooting over phone) at no extra cost to you. We will help you with selecting right solution (including how to manage all of your headset inventory/firmware from cloud using Plantronics Manager Pro). Give us a call at (425)649-9262 or email at info@btpi.com.