Technicolor DTMF sequences

Many SP-mode videotapes duplicated at Technicolor Videocassette beginning in the late '80s and ending in the mid '00s included a sequence of DTMF tones at the start and/or end of the tape. On certain tapes with this sequence, a faint sound of extra tones precedes it. It is not yet known exactly what each tone in the sequence indicates, except there's usually a pause between the first and second tones, the second tone is always 1, the third tone is always #, and the fourth tone is always D. On certain pressings of CBS/Fox releases from early-late 1989, this sequence occurs during the still-imaged 1984-1999 Fox FBI warning screen/1984-2000 CBS/Fox Video logo combo that likely occured on those pressings due to some sort of processing error.