The TN2793B is a dual coded, analog line 24-port circuit pack with Caller ID. Each port supports one telephone, such as the rotary dial 500 telephone and the DTMF dial 2500 telephones. The TN2793B supports on-premises wiring with either touch-tone or rotary dialing and with or without the LED and neon message waiting indicators. The TN2793B supports off-premises wiring with either DTMF dialing or rotary dialing. LED or neon message waiting indicators are not supported off-premises. Along with a TN755B neon power unit per carrier or per single-carrier cabinet, the TN2793B supports
telephones equipped with neon message waiting indicators (on-premises use only). The TN2793B supports three ringer loads, only one telephone can have an LED or neon message waiting indicator. The TN2793B allows a maximum of 12 simultaneous ports ringing; four on ports 1 through 8, four on ports 9 through 16, and four on ports 17 through 24. The TN2793B supports A- and μ-law companding and administrable timers. The TN2793B supports queue warning level lights associated with the DDC and the UCD features, recorded announcements associated with the Intercept Treatment feature, and PagePac paging system for the Loudspeaker Paging feature. Additional support is provided for external alerting devices associated with the TAAS feature, neon message waiting indicators, and modems. The TN2793B also supports secondary lightning protection. The TN2793B provides -48 VDC current in the off-hook state and -90 VDC ringing voltage.