What This Connector Is — 6p4c RJ11/RJ14 Jack with Board Lock
The TE Connectivity 555979-1 is a single-row, 6-position 4-conductor (6p4c) modular jack, wired for RJ11 or RJ14 applications. It is a right-angle, through-hole solder termination jack with a board lock feature for secure PCB retention during wave soldering and in-service vibration. The tab orientation is down, standard for most wall-plate and panel-mount receptacles. It is unshielded and does not contain an LED indicator.
The 555979-1 carries a Cat3 (Category 3) rating, which limits its frequency performance to 16 MHz — suitable for voice and low-speed data (10BASE-T Ethernet, ISDN, analog phone lines). It is not rated for Cat5e or higher (100 MHz+) applications.