DIAL FACILITIES MANAGEMENT PRACTICES DIVISION H AT & TCo Standard SECTION 13b{1) Issue 1, February 1976 SWITCHING SYSTEMS MANAGEMENT NO. 4A AND 4M CROSSBAR SYSTEM DESCRIPTION ELECTROMECHANICAL-CARD TRANSLATOR SYSTEM CONTENTS PAGE CONTENTS PAGE A. Call Through a Combined Train-CT 1. GENERAL 4 Office 11 COMMON CONTROL 4 B. Call Through a Separate Train-CT Office 12 CONNECTORS 5 C. Calls Requiring Outgoing Senders 12 4-WIRE TALKING PATH 5 4. EQUIPMENT ELEMENTS 13 ROUTE TRANSLATION 5 ELEMENTS COMMON TO CT AND ET OFFICES CARD TRANSLATOR 5 13 STORED PROGRAM CONTROL STORE 5 A. Marker 13 2. SWITCHING PRINCIPLES 5 B. Switching Frames and Their Connectors 16 CROSSBAR SWITCH 5 C. Incoming Sender 16 SWITCHING FRAMES 6 D. Sender Link Frame 18 A. Incoming Frames 6 E. Link Controller and Connector 19 B. Outgoing Frames 7 F. Trunk Block Connector 19 JUNCTORS 8 G. Decoder Connector 20 A. Frame Grouping 8 H. Marker Connector 21 B. Switching Trains 9 I. Outgoing Senders 21 C. Offtee Size 9 J. Multifrequency Pulsing Receiving Frame CONTROL OF SWITCHING OPERATIONS 9 21 3. FUNCTIONS OF PRINCIPAL EQUIPMENT K. Multifrequency Current Supply Frame ELEMENTS 10 21 NOTICE Not for use or disclosure outside the Bell System except under written agreement 006 066 Printed in U.S.A. Page 1 SECTION 13b(l) CONTENTS PAGE CONTENTS PAGE L. Frame Identification Frequency Supply I. Plug-in Trunk Test Set 44 Frame 22 J. Frame Identification Frequency Test Set M. Traffic Overload Reroute Control 44 (Manual) 22 TOLL UNE MAINTENANCE EQUIPMENT 45 N. Traffic Control Console 22 A. No. 17-Type Toll Testboard 45 0. Circuit Busy Announcement Trunks 22 B. Patching Bays 45 P. Group Busy Chain Relays 23 c. Automatic Outgoing lntertoll Trunk Q. Trunks and Trunk Relay Equipment 23 Test Frame 45 ELEMENTS PECUUAR TO CT OFFICES 27 ALARMS 46 A. Decoders and Card Translators 27 6. TRAFFIC REGISTERS 46 B. Card Translator 29 FIGURES C. Foreign Translator Connector 35 1. Partial Perspective View of Unit Crossbar D. Emergency Translator Connector 35 Switch (200 Point) • . • 47 E. Alternate Route Traffic Control Frame 2. Schematic of Crossbar Switch ( 10 Horizontal 35 Paths) . 49 5. MAINTENANCE FEATURES 36 3. Schematic of Crossbar Switch (20 Horizontal Paths) 49 SWITCHING MAINTENANCE EQUIPMENT 36 4. Crossbar Switches 51 A. Trouble Recorder Frame 36 5. Channel Between Incoming and Outgoing B. Incoming Sender Test Frame or Incoming Trunks 53 Sender and Register Test Frame 40 6. Path of Call Through Incoming and Outgoing C. Outgoing Sender Test Frame 40 Frames 53 D. Sender Make-Busy Frame 40 7. Incoming Frame 55 E. Automatic Outgoing Toll Connecting 8. Outgoing Frame 57 Trunk Test Frame (AOCT in 4A Offices or ATCT in 4M Offices) 41 9. Junctor Distribution 59 F. Manual Outgoing Trunk Test Frame-Test 10. Single Train-Combined Operation 60 and Make-Busy Frames 43 11. Separate Train-Combined Operation 60 G. Automatic Outgoing Trunk Test Frame for Toll Completing Trunks (AOOT or 12. Relationship Between Common Control AOTT) . 43 Equipment and Switching Frames 61 H. Incoming, Outgoing, and lntertoll Trunk 13. Call Through a Combined Train CT Office Test Set . • 44 63 Page 2 DIVISION H, SECTION 13b(1) CONTENTS PAGE CONTENTS PAGE 14. Call Through a Separate Train CT Office 33. Supplementary Decoder Connector Frame 65 for Use in Separate Train Offices, Combined Train Offices or Office Expanded to Separate 15. Information to Marker 67 Train Combined Operations 84 16. Seizing an Outgoing Trunk 67 34. Marker Connector Frame for Use in Separate Train Offices 85 17. Establishing a Channel 68 35. Outgoing Sender Frame 86 18. Marker Frame 69 36. Multifrequency Current Supply Frame 87 19. Pairing Switching Frames (Home and Mate Operation) 70 37. Frame Identification Frequency Supply and Control Frame 88 20. Access to Incoming Senders-Office Equipped With Flat-Spring MF Incoming Sender 71 38. Traffic Control Frame 88 21. Access to Incoming Senders-Office Equipped 39. Decoder Access to Card Translators 89 With Wire-Spring MF Incoming Sender 72 40. Decoder Frame 90 22. Incoming MF and DP Sender Frame-4M Offices 73 41. Card Translator Cabinet 91 23. Incoming MF and DP Sender Frame-4A 42. Translator Card 93 Offices 74 43. Effect of Dropped Card on Light Channels 24. Incoming Multifrequency Sender Frame-4A 95 Offices 75 44. Card Support and Code Bars Normal 95 25. Overseas Sender 76 45. Card Support and Code Bars Operated 26. Sender Link Frame-Sender Link Spread (Corresponding Card Drops) 95 (MF and DP Senders) 77 46. Elements of the Card Translator 96 27. Incoming or Outgoing Sender Link Frame 78 47. Foreign Translator Connector Frame (For Supplementary Foreign Translator Connector 28. Link Controller Operation 79 Frame) 97 29. Link Controller and Connector Frame 80 48. Emergency Translator Connector Frame (For 18-Decoder Capacity) 97 30. Sender Link Access to Link Controllers 81 49. Trouble Recorder Frame 98 31. Block Relay Frame 82 SO. Trouble Record Cards (Blank) 99 32. Decoder Connector Frame for Separate or Combined Train Offices 83 S 1. Trouble Record Card (Punched) 101 Page 3 SECTION 13b(1) CONTENTS PAGE outside the local or extended service area by direct distance dialing (DDD) and for operator dialing of 52. Incoming Sender and Register Test Frame such calls by "Operator Distance Dialing". The 103 4A/4M switching equipment provides a means for automatically completing connections: (a) between 53. Outgoing Sender Test Frame 104 various long-distance dial trunks {intertoll trunks), (b) between intertoll trunks and trunks which are 54. Sender Make-Busy Frame 105 used to either complete or originate calls in the toll center area (toll connecting trunks). The switching 55. Automatic Outgoing Toll Connecting Trunk equipment is controlled by dial pulses (DP) or Test Frame (AOCT in 4A Offices or ATCT multifrequency pulses (MF) originated by customers in 4M Offices) 106 or long-distance operators. 56. Manual Outgoing Toll Connecting Trunk 1.05 Calls arriving at the 4A/4M toll office may Test Frame 107 have been originated by an operator or customer. Operator and customer calls may be 57. Automatic Outgoing Toll Connecting Trunk given different routing treatment during translation Operational and Transmission Test Frames of the dialed digits by use of an incoming trunk (AOOT and AOTT) 108 class. In a CT office there are only two incoming trunk class indications available for this purpose. 58. Automatic Outgoing lntertoll Trunk Test In an ET office it is possible to have up to 16 Frame and Associated Transmission Test incoming trunk classes so that with the same dialed and Control Frame 109 digits, several different routing choices would be available. Incoming calls are generally routed from the digital information alone. 1. GENERAL 1.06 After the dialed digits have been registered, 1.01 This section provides a description of the the switching control equipment of the 4A card translator (CT) system used in the 4A or 4M system selects a route that can forward and 4M Toll Switching Systems. It covers the the call to the destination. general method of operation when establishing a connection and a description of the equipment elements. Most of the equipment elements used COMMON CONTROL in a CT office will be used inan electronic translator (ET) office with the exception of decoders and card 1.07 Common control is a term applied to certain translators. The equipment elements peculiar to equipment units in the office which are an ET office and general information pertaining to common to many of the switching frames which the elements are covered separately in Dial Facilities set up a talking connection. A common control Management Practices (DFMPs), Division H, Section system has the ability to store, alter, and reuse 13c(2). Centralized automatic message accounting digits. Some of the common control circuits are: (CAMA) operation is discussed onlywhere necessary markers, senders and link controllers, as well as for clarity. decoders and card translators in a CT office, or decoder channels, distributor registers, and the 1.02 Whenever this section is reissued, the reason stored program control (SPC) in an ET office. for reissue will be listed in this paragraph. Some common control circuits associated with the CAMA portion of the 4A/4M systems are: 1.03 The title for each figure includes a number(s) transverters, billing indexers, recorders, position in parentheses which identifies the paragraph(s) link controllers, and master timers. in which the figure is referenced. 1.08 The common control equipment is used on 1.04 The 4A/4M Toll Switching System is a part each call only long enough to set up a of the distance dialing network for customer talking connection, after which it releases and is and operator dialing of toll calls. The network ready to serve another call. In this manner a few provides for customer dialing of calls to points units of complicated equipment are used for short Page 4 DIVISION H, SECTION 13b(1) periods of time to set up the switches for a translation system. In a CT office, information proportionately large number of calls. for routing calls is contained on metal cards which are stored in card translators. In an ET office, CONNECTORS information for routing calls is stored in the memory store portion of a SPC complex. 1.09 Connectors are used to connect various common control equipment to each other CARD TRANSLATOR temporarily during the process of setting up a call. This is done by a group of multicontact relays in 1.15 The card translator is an electromechanical the connector which cut through a number of leads device which uses metal cards, electron between circuits. Connectors are equipped with a tubes, phototransistors, and transistor amplifiers chain (or preference) circuit which causes the to perform its functions.