Old Bell System/AT&T phone wiring and any technician that worked for them would have been fired making that mess. They would never use electrical tape. They would use crimp splices that had an insulating "goo" in them. This looks like an amateur job.
The old Western Electric Princess and Trimline phones would use the black/yellow pair in the jack to be used with a "wall wart" transformer that plugged into an AC outlet to power the dial/touch tone lamps on those phones. When the later models of those phones were converted to LEDs for the dial/touch tone illumination, the black/yellow pair in the jack could be used for a two line phone that used one jack for both lines.
Old Bell System/AT&T phone wiring and any technician that worked for them would have been fired making that mess. They would never use electrical tape. They would use crimp splices that had an insulating "goo" in them. This looks like an amateur job.
The old Western Electric Princess and Trimline phones would use the black/yellow pair in the jack to be used with a "wall wart" transformer that plugged into an AC outlet to power the dial/touch tone lamps on those phones. When the later models of those phones were converted to LEDs for the dial/touch tone illumination, the black/yellow pair in the jack could be used for a two line phone that used one jack for both lines.