Hardware Conferencing for Cisco Unified SIP IP Phones
In Cisco Unified CME 9.0 and later versions, the SIP line side hardware conference support enables a Cisco Unified SIP IP phone to act as the creator of ad-hoc and meet-me conferences with audio and video conferencing streams flowing from participating IP phones through the Cisco Unified CME.
Cisco Unified 7906, 7911, 7941, 7942, 7945, 7961, 7962, 7965, 7970, 7971, 7975, 8961, 9951, and 9971 SIP IP Phones can be conference creators that automatically initiate hardware conference calls.
Voice Hardware Conferencing
Voice hardware conferencing requires provisioning a DSPFarm voice profile with the appropriate voice codecs.
The voice hardware conference resource is allocated and released whenever a participant joins and leaves a conference call.
Table 1 lists the limit on the number of participants for voice hardware conferencing.
Table 1 Maximum Number of Voice Hardware Conferencing Participants
Voice Hardware Conference
Maximum Number of Participants
Video Hardware Conferencing
Video hardware conferencing requires provisioning a heterogeneous DSPFarm video profile with the appropriate video codecs and resolutions.
Once the video profile is available, the SIP line side conference creator can add any type of video-capable IP phone (Cisco Unified 7906, 7911, 7941, 7942, 7945, 7961, 7962, 7965, 7970, 7971, 7975, 8961, 9951, and 9971 IP Phones) to create an ad-hoc or meet-me video conference.
For other participants, Cisco Unified Video Advantage (CUVA) and Cisco Unified 7985 SCCP IP Phones are also supported.
The video hardware conference resource is allocated and released whenever a participant joins and leaves a conference call.
Table 2 lists the limit on the number of participants for video hardware conferencing.
Table 2 Maximum Number of Video Conferencing Participants
Maximum Number of Participants
In Cisco Unified CME 9.0 and later versions, voice-activated (loudest speaker) video switching is supported.
Meet-Me Hardware Conferencing
A meet-me conference is a scheduled conference and takes place when the conference creator goes offhook, presses the MeetMe soft key or feature button, and dials the meet-me conference directory number (DN). Participants can then dial the meet-me DN to join and connect to the conference bridge. The phone’s display shows the meet-me DN as the remote party ID.
With the unlock feature in Cisco Unified CME 9.0 and later versions, there is no need to press the MeetMe soft key to initiate voice or video conferencing and any Cisco Unified SIP IP phone can initiate the call.
Meet-me conferences are straightforward. The conference creator explicitly chooses to make a voice or video call by dialing a voice or video DN.
Ad-Hoc Hardware Conferencing
For Cisco Unified CME 9.0 and later versions, Cisco Unified SIP IP phones act as ad-hoc conference creators while Cisco Unified SIP or Cisco Unified SCCP IP phones act as the participants.
Ad-hoc conference calls are unscheduled conferences and occur when the conference creator adds a third party into the call. However, only consultative conferences, where the creator commits after the consultative party is connected, are supported in these conference calls.
The creator may add participants to the conference until the maximum number of participants is reached.
If the conference is configured to stay, the conference will fall back to a point-to-point call and the conference bridge resource is released when participants leave the conference, leaving only two parties.
Voice (or audio, to avoid confusion in the table) and video calls are connected to an ad-hoc conference bridge based on the following rules. See Table 3 for examples.
Cisco Unified CME reserves a video conference DN if:
– Either the primary or consultative call is a video call (See rows 3 and 4.)
– Both the primary and the consultative calls are video calls (See row 2.)
Otherwise, an audio conference DN is reserved. (See row 1.)
When the conference creator’s primary and consultative calls have different capabilities, regardless of which one is audio, the creator’s call results in a video call to the conference bridge. (See rows 3 and 4.) The audio conference call leg is disconnected.
Audio conference calls remain audio and cannot be upgraded into video calls. When a conference creator has one video conference call, the conference DN and the resulting conference call are video. However, when the creator has two active conferences using different media, the creator’s video conference with one set of participants does not affect the creator’s audio conference with the other set of participants.
In row 4, the primary call between A and B is video and the consultative call between A and C is audio. Although C is in a call with the video-capable creator A, C remains an audio call and does not upgrade into a video call connecting to the video conference bridge.
There is no mid-call media renegotiation for all parties after the primary and consultative calls are established. The call capabilities do not change after they are redirected to the bridge.
Table 3 Voice (Audio)/Video Ad-Hoc Conferencing
(A and B)
Call (A and C)
Resulting Conference (A)
Resulting Conference (B)
Resulting Conference (C)
In row 2 of Table 3, when a conference is initiated from a video-enabled IP phone, the conference call is video.
However, in row 4, when a video-enabled IP phone initiates a conference with an audio-only phone, the conference remains audio.
Row 4 of Table 4 shows that when audio-only IP phone A initiates a consultative call with video-enabled IP phone D and D joins the active ad-hoc conference as a fourth participant, the resulting conference remains audio.
Table 4 Adding a Fourth Participant to an Active Ad-Hoc Conference
During a conference, any of the participants can press the ConfList soft key to display a list of the current participants of the conference call but only the creator or administrator can remove a participant from the list. Once the conference list is displayed, the creator or administrator can navigate through the list and remove any participant by pressing the Remove soft key.
The Remove soft key is useful in removing an unidentified participant or a conference participant who does not display a caller ID.
The conference list is static and you need to press the Update soft key to refresh the list to reflect the addition or removal of a participant. Aside from the soft key, you can also enable the feature through programmable line keys (PLK).
NoteCisco Unified 8961, 9951, and 9971 SIP IP Phones enable the Show Detail soft key to perform the conference list function when an active conference call is detected. However, the conference list cannot be displayed when a Cisco Unified 8961, 9951, or 9971 SIP IP Phone is on an active video conference because the Show Detail soft key is not enabled. Cisco Unified 8961, 9951, and 9971 SIP IP Phones enable the Show Detail soft key to perform the conference list function when an active conference call is detected. However, the conference list cannot be displayed when a Cisco Unified 8961, 9951, or 9971 SIP IP Phone is on an active video conference because the Show Detail soft key is not enabled.
Remove Last Conference Participant
During an ad-hoc conference, the creator can press the RmLstC soft key or use the Remove Last Participant PLK to drop the last added participant.
This feature is not relevant to meet-me conference calls and is only available to conference creators and system administrators.
Supplementary Services Interaction
In Cisco Unified CME 9.0 and later versions, hardware conferencing supports Hold and Resume on SIP-only shared lines but not on mixed SIP-SCCP shared lines.
How to Configure Voice and Video Hardware Conferencing
(Optional) Configures the mode for adding participants to ad-hoc hardware conferences on Cisco Unified SIP IP phones.
Default is that the conference creator or any of the participants can add a new participant.
creator —Specifies that only the conference creator can add participants to an ad-hoc hardware conference.
conference drop-mode [ creator | local ]
Router(config-register-pool)# conference drop-mode local
(Optional) Specifies who can terminate an active hardware conference by hanging up.
Default is that an active conference is never dropped.
creator —The active conference is terminated when the conference creator hangs up.
local —The active conference is terminated when the last local participant hangs up or drops out of the conference.
Exits to privileged EXEC mode.
Use debug commands to display debugging information on hardware conferencing.
The following example is a partial output from the debug ccsip event , debug ephone hw-conference , and debug ephone mtp commands. The debug ccsip event command enables the collection of events that are specific to service provider interface (SPI) for debugging purposes. The debug ephone hw-conference command enables the collection of debugging information on hardware conferencing for Cisco Unified SCCP IP phones. The debug ephone mtp command enables Message Transfer Part (MTP) debugging.
Mar 17 22:08:21.867: //21/E2793E678024/SIP/Info/ccsip_indicate_rt_packet_stats: Processing stats for callid=21, proc_id=9
Mar 17 22:08:22.027: //-1/xxxxxxxxxxxx/SIP/Info/HandleUdpIPv4SocketReads: Msg enqueued for SPI with IP addr: [188.8.131.52]:49706, local_address:[ - ]
Mar 17 22:08:22.027: //-1/xxxxxxxxxxxx/SIP/Info/ccsip_process_sipspi_queue_event: ccsip_spi_get_msg_type returned: 2 for event 1
Mar 17 22:08:22.027: //-1/xxxxxxxxxxxx/SIP/Info/ccsip_new_msg_preprocessor: Checking Invite Dialog
Mar 17 22:08:22.027: //-1/xxxxxxxxxxxx/SIP/Info/sipSPIAddContextToTable: Added context(0x2995490) with key= to table
Mar 17 22:08:22.027: //-1/000000000000/SIP/Info/ccsip_offer_ans_init:
Mar 17 22:08:22.027: //-1/000000000000/SIP/Info/ccsip_iwf_init:
Mar 17 22:08:22.027: //-1/000000000000/SIP/Info/ccsip_ipip_media_service_init:
Mar 17 22:08:22.027: //-1/000000000000/SIP/Info/sipSPI_ipip_vcc_Initialization: Entry...
Mar 17 22:08:22.027: //-1/xxxxxxxxxxxx/SIP/Info/resolve_sig_ip_address_to_bind: calling reg_invoke_ip_first_hop()
Mar 17 22:08:22.027: //-1/xxxxxxxxxxxx/SIP/Info/resolve_sig_ip_address_to_bind: calling ip_best_local_address()
Mar 17 22:08:22.027: //-1/xxxxxxxxxxxx/SIP/Info/resolve_sig_ip_address_to_bind: return addr 184.108.40.206
Mar 17 22:08:22.027: //-1/xxxxxxxxxxxx/SIP/Info/sipSPISetDateHeader: Clock Time Zone is UTC, same as GMT: Using GMT
Mar 17 22:08:22.031: //-1/000000000000/SIP/Info/sipSPILineControlMsg: nSS_CONF_REQUEST
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NoteTable 5 lists the Cisco Unified CME version that introduced support for a given feature. Unless noted otherwise, subsequent versions of Cisco Unified CME software also support that feature.
Table 5 Feature Information for Voice and Video Hardware Conferencing
Cisco Unified CME
Voice and Video Hardware Conferencing
Enables a Cisco Unified SIP IP phone to act as the creator of ad-hoc and meet-me conferences with audio and video conferencing streams flowing from participating IP phones through the Cisco Unified CME.