RJ-31X: Provides a series connection to the tip and ring conductors of a telephone line. It's wired ahead of all station equipment electrically and is typically used with registered alarm-reporting devices. When there's an alarm condition, the registered device functions to cut off all station equipment wired behind it, via this jack.

RJ-32X: Provides a series connection to the tip and ring conductors of a telephone line. It differs from RJ-31X in that it's wired ahead of a particular telephone set rather than ahead of all the station equipment. It's typically used with registered automatic dialers.

RJ-33X: Is normally associated with a key telephone system. It provides a series connection to the tip and ring conductors of the telephone line and the key-system line circuit A and Al leads. The tip and ring conductors are wired ahead of the key-system line circuit. This arrangement is typically used when the modem requires central office or PBX ringing.

RJ-34X: Is normally associated with a key telephone system. It's wired to provide a series connection to the key-system line circuit tip and ring conductors and its A and Al leads. It differs from RJ-33X in that all conductors are wired behind the key- system line circuit. This arrangement is typically used when the modem is not critical as to type of ringing signal or doesn't require central office or PBX ringing.

RJ-35X: Is normally associated with a key telephone set. It's wired to provide a series connection to the tip and ring conductors of the telephone line and a bridged connection to the A and Al leads. It differs from RJ-33X and RJ-34X in that the tip and ring leads are connected to the common wiring behind the pickup keys of the station set but ahead of the switch hook. The jack is wired to the key telephone set so that the modem functions on the line selected on the key telephone set.

RJ-36X: Provides a connection for a registered telephone set equipped with an exclusion key when the telephone line is also to be used with a registered data set or registered protective circuitry. It's wired to provide a series connection to the tip and ring conductors of the telephone line and mode- indication leads MI and MIC. With this jack, the exclusion key can be used to transfer the telephone line between the modem and the telephone set. As a customer option, the exclusion key may be wired so that either the telephone set or the modem controls the line. In the former case, the exclusion key must be operated to transfer the telephone line to the modem. In the latter case, the telephone line is normally associated with the modem. Operation of the exclusion key is required to transfer the line to the telephone set. In either case, a closure on the MI and MIC leads indicates the voice mode.

RJ-37X: Is used for providing two-line service with exclusion. The jack is wired to provide a bridged connection to the tip and ring conductors of two telephone lines with exclusion on line 1. RJ-18C: Provides a bridged connection of single-line tip and ring with make-busy leads M13 and MB1. When the registered equipment provides a contact closure between the MB and MB1 leads, a make-busy indication is transmitted to the network equipment busying out the line from further incoming calls. It's recommended that the busy indication (contact closure) be provided while the line is in the idle state in order to reduce the possibility of interfering with a call that is in the ringing or talking state. The RJ-18 EIC is surface or flush mounted for use with desk telephone sets.

RJ-38X: Provides a series connection to the tip and ring conductors of a telephone line identical to those described for RJ-31X. However, the jack also provides a continuity circuit which is used as an indication that the plug of the registered equipment is engaged with the jack. The jack is wired ahead of all station equipment electrically and is typically used with registered alarm dialers.