The T4 is designed to serve as both the transmitter and repeaters for the I-Caption, D-Scriptive and ShowTrans systems. It transmits cue information from the control station to R4 audio and video hand-held receivers. The fully automated system is designed to display captions, audio description or multilingual commentary to wireless receivers.

The T4 Transmitter when coupled with the R4 Receiver and the CS3 Control Unit will display I-Caption slides of verbatim closed captions or subtitling. The T4 can also trigger playback of prerecorded audio files in mp3 format on the R4 for audio description for the blind or multi-lingual audio commentary.