Handset not working when plugged into headset base
When the headset base is set to DHSG, it turns off the handset port. So move it down to RHL to make it work
Note: If you move the switch, make sure to perform a resync so that the headset will work again
If all the connections and compats are good (set to RHL), then sometimes it can be due to a faulty base, even if the headset works fine. In this case, we would need to replace the whole unit, as the problem is in the base.