/mcpendpoint and MTP/transcoder, codec mismatch between the endpoint and the MTP/transcoder; a lack of available bandwidth between the endpoint and the MTP/transcoder; or because the MTP/transcoders resources are already in use. A capability mismatch may be due to the MTP/transcoder not supporting one or more of the required capabilities for the call such as Transfer Relay Point (which is needed for QoS or firewall traversal), RFC 2833 DTMF (which is necessary when one side of the call does not support RFC 2833 format for transmitting DTMF digits and the other side must receive the DTMF digits in RFC 2833 format, resulting in conversion of the DTMF digits), RFC 2833 DTMF passthrough (in this case, the MTP or transcoder does not need to convert the DTMF digits from one format to another format but it needs to receive DTMF digits from one endpoint and transmit them to the other endpoint without performing any modifications), passthrough (where no codec conversion will occur, meaning the media device will receive media streams in any codec format and transmit them to the other side without performing any codec conversion), IPv4 to IPv6 conversion (when one side of the call supports only IPv4 and the other side of the call supports only IPv6 and so an MTP needs to be inserted to perform the necessary conversion between IPv4 and IPv6 packets), or multimedia capability (if a call involving video and/or data in addition to audio requires insertion of an MTP or transcoder then the MTP/transcoder which supports multimedia will be inserted). Recommended Action If the MTP or transcoder allocation is failing due to a capability mismatch, it's possible that the media device does not support the capability (such as IPv4 to IPv6 conversion, passthrough) or the capability might not be configured in the device. Please check the user guide and documentation of the media device to make sure that device supports all the necessary capabilities. Also, caution should be taken if all the MTP or transcoders are configured with all the supported capabilities. There are certain capabilities (such as RFC 2833 DTMF or RFC 2833 DTMF passthrough or passthrough) which could be supported by most of the MTPs or transcoders and there may be certain capabilities (such as IPv4 to IPv6 conversion and vice versa or Transfer Relay Point or multimedia capability) which can be supported by only by a single MTP or transcoder depending on the devices that you have. For example, you may have IP phones that support only IPv4 protocol and there may also be IP phones that support only IPv6 protocol. To make a call between IPv4-only and IPv6-only phones, you need to have an MTP configured to perform the conversion of IPv4 to IPv6 and vice versa. However, suppose all the MTPs or transcoders are configured with all the supported capabilities and only one MTP supports IPv4 to IPv6 conversion; if this MTP is configured with all the supported capabilities (which all the other MTPs or transcoders in the same MRGL or default MRGL also support) it may happen that this MTP can get allocated for Transfer Relay Point or RFC 2833 DTMF or RFC 2833 DTMF passthrough or passthrough instead. As a result, when the need arises for IPv4 to IPv6 conversion (which other MTPs or transcoders in the same MRGL or default MRGL do not support), all the resources of MTP may be in use and the IPv4 to IPv6 conversion may fail. To avoid this kind of problem, setting the priority of the media resources may be a good idea. This can be done only in the Media Resource Group List and not in the Default List of the media resources. In any Media Resource Group List all the Media Resource Groups have different priorities; during allocation the first Media Resource Group is always checked for availability of the requested type of the media devices. The first Media Resource Group in the Media Resource Group List will have the highest priority, then the second one, and so on. To check all the Media Resource Groups and their priority go the Media Resources and Media Resource Group List of Cisco Unified CM Administration page and click the appropriate Media Resource Group List and check the Selected Media Resource Groups; the priority decreases from top to bottom. So, the MTP or transcoder that you want to be selected for the most basic functionalities should be positioned in the higher priority Media Resource Groups whereas the ones with more rare functionality should be positioned in the Media Resource Groups with lower priority. MTP/transcoder allocation may fail due to codec mismatch between the endpoint and the MTP/transcoder. A solution may be to configure the MTP/transcoder with all the supported codecs (as specified in the user guide of the MTP/transcoder), but be aware that doing so might result in too much bandwidth being allocated for calls. You'll need to weigh different factors such as the total amount of available bandwidth, the average number of calls, approximate bandwidth use per call (not involving 5/24/26, 3:34 AM System Error Messages for Cisco Unified Communications Manager 15 - Cisco https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/err_msgs/15_x/ccmalarms15.html 261/343