i've got a headset that works on a 7316. but those phones have a headset-specific button, the 7324's don't. it's a fellows monaural e250x. there is no switch on the headset. just a cord straight to a headset. if the headset is not plugged in, and i hit handsfree/mute, the speakerphone comes up. if it IS plugged in, and i hit handsfree/mute, nothing happens.