KTU	Circuit Function	Size	Contacts	Quanity needed	BSP
400 B (1) C D (35) G (6) H (16)	CO/PBX Line	4	18	1 per line
401 A ISS 4 (2) A ISS 7 (1) B	Manual Intercom Line	4	18	As required
402 A	Diode Matrix for Common Audible Signal Control	Not plugin type KTU mounts on 501 or 502 KSU		1 per 4 lines and 12 signals or vise versa
404 A	Diode Matrix for Common Audible Signal Control	4	18	1 per 6 lines and 12 signals or vice versa
405 A	Multi-line Exclusion	4	20	1 per 2 lines
406 A	Supplementary Hold Detector	4	18	1 per 2 lines or stations
407 B   C	Dial Intercom 10-Code Selector	8	80	1 per intercom system
408 A	Flutter Generator	4	18	1 per 100 lamps and 20 supplementary and/or regular hold keys
412 A	Auxiliary Lamp Relay	Special-Requires a KS-8586, L32 connector		Used in place of interrupter for LW and LF functions
413 A	Auxiliary Ringup	4	18	As required
414 A & M Only	Manual Signaling, Ringdown Private Line	4	20	2 per line (1 at each end*)
415 A B (6)	Automatic, DC Signaling Private Line	4	18	2 per line (1 at each end*)
416 A	Station Line	4	20	1 per line
417 A	Add-On Confrence	4	40	1 per confrence circuit
418 A	Short Range, DC Signaling Private Line	4	20	1 per line
419 A	Automatic Signaling, Ringdown Private Line	8	80	2 per line (1 at each end*)
420 A	Dial Intercom Long Line	4	18	1 per off-premise line
421 A	Power Failure Transfer General Purpose Relay, DSS, or Audible Signaling Suppression	4	40	1 per common audible transfers 1 per DSS code 1 per ringer or buzzer or as required
422 B	Station Busy Selector	4	4	1 per 10-code intercom 2 per 19-code intercom
423 A	Dial Tone, Busy Tone, and Audible Ringback Tone	4	20	1 per intercom system (not for use in modular panels)
424 A C (2)	Dial Intercom 19-Code selector	8	80	1 per intercom system
425 B	Flashing Lamp	8	80	1 per intercom system
426 A (1) B   C	TOUCH-TONE Adapter	8	80	1 of each required per intercom system
		8	80
428 A	Multiline Exclusion	4	40	2 per 2 lines
429 A   B	Supplementary Hold Detector	4	40	1 per 2 li nes or stations
430 A	Flutter Generator	4	20	1 per 100 lamps and 20 supplementary and / or regular hold keys
440 A	TOUCH-TONE Adapter	8	80	1 per intercom system
444 A 444 B	Selector Extender	8	80	1 per intercom system
448 A	Delayed Transfer Control	4	40	1 per 2 lines
449 A	Immediate Transfer Control	4	40	1 per 2 lines
451 B (2)	Music-On-Hold	4	40	1 per 7 lines (not compatible with 400H KTU)
452 A	Power Failure Ringing	4	40	1 per 7 li nes
454 B   C	3-Path Intercom	8	80	1 per intercom system
455 A	Tone Ringing Sigmal Generator	4	40	1 per system
456 B	Voice and tone Alerting circuit	8	40	1 per intercom system
457 C	Paging Amplifier	8	40
460 B 460 C	2-Path Intercom	8	80	1 per intercom system
461 A (2)	Manual Signaling, Ringdown Private Line	4	18	2 per line (1 at each end*)
467 A	Low-Voltage Monitor	4	18	1 per system
469 A	Lamp Driver	4	18	1 per line per each 20 excess lamps
470 A	External Signal	4	20	1 per 2 lines requiring external signaling
471 A 471 B	Battery Reversal Toll Restriction	4	18	1 per CO line
476 A	Dial Tone, Busy Tone, and Audible Ringback Tone	4	20	1 per intercom system (for use in 642A modular panel)
478 B (1)	TOUCH-TONE Adapter	8	80	1 per intercom system
479 A   B	Rotary Dial Toll Restriction	8	20	1 per CO line
494 A	TOUCH-TONE Selector	8	20	1 per intercom system
498 A	Music-On-Hold	4	40	Provides music-on-hold for 4 lines, with addition of 116Al CM. Music-on-hold is provided on additional 3 lines

* Terminating end must be a similar or equivalent tie line unit.