In general, Mute and Unmute are automatic functions. However, IP phones have an enhancement that can be configured on a per set basis.

There is one CS 1000 and Device Adapter item where this differs from generic mute. When an IP phone has the Mute key allowed (MUTA) class-of-service, the typical behavior experienced on all other endpoints applies. MUTA is a Device Adapter feature.

However, if the endpoint is configured with the Mute key denied (MUTD) feature, the button is still present. But, instead of muting the call, the button places the call on hold, possibly with an on-hold music.

In a MUTD IP phone, the Mute button can be a toggle, which places the call on hold and retrieves the call.

For more information, see Mute in Appendix G: Generic station operations.