As specified in [ETSI TS 124 182], the customized alerting tone (CAT) service is an operator specific service by which an operator enables the subscriber to customize the media which is played to the calling party during alerting of the called party. As specified in [ETSI TS 124 183], the customized ringing signal (CRS) service is an operator specific service by which an operator enables the subscriber to customize the media which is played to the called party during alerting of the called party.

For both services the media can consist of user's favourite songs, multi-media clips or other customized alerting tones. When the media consists of video clips, it is called video CAT and video CRS service, respectively. High definition (HD) video CAT and CRS service can provide high-definition, full-screen video.

In order to assess the quality of experience (QoE) of a specific video CAT or video CRS service, analysis of influencing factors is critical. Compared with traditional video and audio, the short-time experience in video CAT and CRS imposes a new set of requirements to QoE assessment. The challenge is to characterize video CAT's real-life short video, terminal display strategy, and interactivity.

This Supplement categorizes and summarizes the major factors that affect user-perceived experience of a HD video CAT and CRS service, with the intention to help identify the methodologies for assessing the video CAT or CRS quality.