/mcpInteraction Feature Intercom can support phones with an IP Addressing Mode of IPv4 Only or IPv4 and IPv6. During an intercom call, the talkback mode establishes media streams with the same IP version as the media stream that is used when the caller initiates intercom. Internet Protocol Version 6 (IPv6) Intercom directory numbers (lines) are restricted to one device per intercom line. Cisco Extension Mobility is widely used; mobile users need the intercom feature but need it to be available only on a single device. You can assign intercom lines to either a regular device or to an extension mobility profile, but the system needs to enforce that an intercom line gets associated to either a regular device or to an extension mobility profile. Intercom directory numbers (lines) An extension mobility profile can be used on more than one phone simultaneously, use the Default Activated Device field in the Intercom Directory Number Configuration window ( Cisco Unified CM Administration > Call Routing > Intercom > ntercom Directory Number Configuration) to specify which device can display this intercom line. Intercom lines that are not used for Extension Mobility also require configuration of the Default Activated Device field. Extension mobility profile Intercom Restrictions The following restrictions apply to the Intercom feature: Restrictions Feature The system does not allow intercom calls to be placed on hold. Hold Intercom calls cannot be forwarded. Call Forwarding The system does not allow an intercom call to be transferred. Transfer The system does not allow an intercom call to be diverted. iDivert The call pickup groups do not include intercom calls. Call Pickup/Directed Call Pickup Intercom overrides Do Not Disturb (DND). DND If sufficient bandwidth does not exist, the intercom call fails. Bandwidth If two intercom calls are directed to a target, the first one goes through; the second fails with a busy tone. Call Target Intercom does not work with Barge and cBarge. Barge and cBarge The system does not allow intercom calls to be in conference. Conferencing When an active call is being monitored or recorded, the user cannot receive nor place intercom calls. Monitoring and Recording Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs 317 Placing Calls Intercom Restrictions