RJ refers to Registered Jack, which represents a registered jack. USOC (Universal Service Ordering Codes) code from Bell Systems. The USOC is a series of registered jacks and their wiring that was developed by Bell Systems to connect users' devices to the public network.
RJ11 is the generic name for connectors developed by Western Electric Co. Its shape is defined as a 6-pin connector. Formerly known as WExW, where x means 'active', contact or wire pin. For RJ11, the source of information is contradictory. It can be a 2- or 4-pin 6-pin connector. Even more confusing is that the RJ11 is not only used to represent the 6-pin connector, it is also referred to as the 4-pin version.
RJ12 is a standard telephone crystal head (six core).
In the cash box interface, RJ11 is a quad core and RJ12 is a six-core.
A brief introduction to the crystal connector:
RJ45: 8-pin plug, 8P8C (8 position, 8 contact), is 8 positions, 8 contacts
RJ12 (RJ25): 6-pin plug, 6P6C, is 6 positions, 6 contacts
RJ11 or RJ14: 4-pin plug, 6P4C, 6 positions, 4 contacts, (such as our telephone access line)
RJ12 (RJ10 or RJ9): 4-pin plug (telephone handset line), 4P4C, 4 positions, 4 contacts
RJ11, RJ14, RJ25 can be used in the same 6-pin 6P6C jack. Generally, RJ11 uses 2 wires, RJ14 uses 4 wires, and RJ25 uses 6 wires.
The cash box connector generally involves RJ11 (6P4C, 4-core) and RJ12 (6P6C, 6-pin). RJ11 and RJ12 can be used in a 6-pin, 6P6C jack. If the customer is not sure that RJ11 or RJ12 should be used, the RJ12 is the safest approach. The RJ12 interface supports micro switches. The micro switch can record the number of times the cash box is opened, because some POS machines do not have this function, so there is no effect on whether the customer uses the cash box for the use of the micro switch.