System Configuration Guide for Cisco Unified Communications Manager Release 15 and SUs - Configure Media Resources

Publisher

Cisco Systems

URL

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/15/systemConfig/cucm_b_system-configuration-guide-15/cucm_b_system-configuration-guide-14_chapter_01011.html

Published

2026-09-22

Updated

unknown

Accessed

2026-09-25

HTTP status

200

License

Cisco documentation terms; no-redistribution; short excerpts and locators only

Source notes citing this source

• By default an annunciator supports 48 simultaneous media streams. in context
• The annunciator is an SCCP software device that lets Unified CM play prerecorded messages and tones to devices. in context
• By default an individual device uses the media resources assigned to the device pool that it is in. in context
• In Release 15, whether a call fails when no MTP or TRP can be allocated depends on the service parameters Fail Call If MTP Allocation Fails and Fail Call If Trusted Relay Point Allocation Fails. When these are not enabled, the call proceeds without the resource. in context
• Activating the Cisco IP Voice Media Streaming service enables the annunciator, IVR, MTP, software conference bridge and music on hold resources on Unified CM. in context
• The IVR device lets Unified CM play prerecorded feature announcements, and by default an IVR supports 48 simultaneous callers. in context
• A media resource group can contain annunciators, IVRs, conference bridges, MTPs, MOH servers and transcoders. in context
• Media resources become available to calls by being placed in a media resource group list (MRGL), which is then assigned to a device pool or to an individual device. in context
• An MRGL is a prioritized list of media resource groups, and resources are selected from the available groups in the priority order defined in the list. in context
• Neither the system's users nor the endpoint on whose behalf an MTP was inserted can see that the MTP is in use. in context
• When Unified CM determines that a call endpoint requires an MTP, it allocates the resource from the MTP that has the fewest active streams. in context
• One use that Unified CM 15 lists for an MTP is resolving mismatches in DTMF transport between call legs. in context
• One use that Unified CM 15 lists for an MTP is delivering SIP Early Offer over SIP trunks. in context
• For H.323 supplementary services, an MTP is required only for endpoints that support neither Empty Capability Set (ECS) nor FastStart. in context
• One use that Unified CM 15 lists for an MTP is converting RTP streams between IPv4 and IPv6. in context
• The Release 15 guide names three MTP implementations: software MTPs in IOS gateways, hardware MTPs in IOS gateways, and the software MTP provided by the Cisco IP Voice Media Streaming service. in context
• Unified CM's own software media service probably cannot transcode, so codec conversion such as G.711 to G.729 likely needs a DSP-based transcoder in an IOS or IOS XE gateway. inferred in context
• The Unified CM 15 media resource types are annunciators, interactive voice response (IVR), media termination points (MTP), transcoders, trusted relay points, conference bridges, and music on hold/video on hold. in context
• On a 10-Mb network or NIC, the Unified CM software MTP can provide approximately 24 MTP resources. in context
• The Cisco Media Termination Point Software type provides 48 MTP resources by default, and the number can be changed. in context
• The Release 15 media resources task flow activates software media resources (the Cisco IP Voice Media Streaming service) first. It then configures MTPs, transcoders, IVR and the annunciator, then media resource groups, then MRGLs, and then assigns them to a device or device pool. Announcements are optional later steps. in context
• A transcoder converts an input stream in one codec into an output stream in a different codec. Unified CM inserts a transcoder when a call's endpoints use different voice codecs. in context
• When a call needs both transcoding and MTP functions, Unified CM allocates a transcoder, because a transcoder can provide both functions at the same time. in context
• The transcoder types listed in the Release 15 guide are Cisco Media Termination Point Hardware, Cisco IOS Media Termination Point (hardware), Cisco IOS Enhanced Media Termination Point (hardware) and Cisco Media Termination Point (WS-SVC-CMM). All are hardware types. in context
• A Trusted Relay Point (TRP) is an MTP or transcoder that Unified CM can insert into the media stream. A transcoder is made available as a TRP by checking the Trusted Relay Point check box. in context
• Unified CM allocates transcoders and MTPs from the Media Resource Group List assigned to the device or its device pool, in priority order. in context
• If codec conversion is required and no hardware transcoder is available, the Unified CM call fails. in context
• From Unified CM 14SU3, secure MTP is supported from the gateway side for DTMF translation with IOS XE 17.10.1a or later gateways. in context
• When a call needs both MTP and transcoding functions Unified CM can allocate a transcoder, because a transcoder can provide both at the same time. in context
• Unified CM invokes a transcoder when the endpoints in a call use different voice codecs, converting one codec stream into another such as G.711 to G.729. in context

Cite this source record

APA

WarmTransfer. (2026, September 22). System Configuration Guide for Cisco Unified Communications Manager Release 15 and SUs - Configure Media Resources. WarmTransfer. https://warmtransfer.net/knowledge/sources/cisco-cucm-sysconfig-15-media-resources

BibTeX

@misc{warmtransfer-cisco-cucm-sysconfig-15-media-resources,
  title  = {System Configuration Guide for Cisco Unified Communications Manager Release 15 and SUs - Configure Media Resources},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/sources/cisco-cucm-sysconfig-15-media-resources},
  note   = {Cisco Systems, accessed 2026-09-25}
}