Bell Systems Letters and Memos

Section Date Issue Size Title
GL 69-11-1281969-11-191.08 MBPBX Systems - 810A Self Contained Electronic PBX
GL 70-08-0601970-08-13325.20 KBPBX Systems: 757A PBX Connection to Traffic Measurement System No. 1A (Also EL 737)
GL 70-10-1231970-10-16688.90 KBPBX System - 802A Electronic PBX
GL 70-10-1791970-10-30480.54 KBPBX Systems - 800A PBX - Custom and Standard Packages (Also EL 875, EM 1190)
GL 70-11-1081970-11-1946.38 KBTraffic Business Services Facilities - 802A Electronic PBX
GL 71-01-0231971-01-07406.07 KBPBX Systems - 770A Crossbar PBX
GL 71-01-0901971-01-14245.19 KBCustomer Telephone Facilities - 805A PBX - Traffic Business Services Facilities Engineering Information
GL 71-02-0081971-02-02589.93 KBPBX Systems - 800A PBX - Growable Network (Also EL 1020)
GL 71-02-1141971-02-22153.85 KBPBX Systems - 756A PBX Connection to Traffic Measurement System No. 1A (Also EL 1097)
GL 71-04-1051971-04-1488.02 KBPBX Systems: 756 and 757 PBX Connections to Traffic Measurement System No. 1-A
GL 71-06-0091971-06-01796.97 KBCustomer Telephone Facilities - 770 PBX - Traffic Business Services Facilities Engineering Information
GL 71-07-0371971-07-08314.30 KBCustomer Telephone Facilities - 770 PBX - Traffic Business Services Facilities Engineering Information
GL 72-03-1181972-03-20372.29 KBInterconnection - Interface Between ACDs (2A and 3A) and Customer-Provided Traffic Measuring Equipment (Also EL 1679)
GL 72-04-0111972-04-064.47 MBDATASPEED 2101AB RO Printer (Also EL 1537)
GL 72-04-0931972-04-201.37 MBCustomer Telephone Facilities - 770A PBX - Traffic Business Services - Facilities Engineering Information
GL 72-05-0381972-05-1274.46 KBTraffic Business Services Facilities Engineering Practices - Attendant Facilities - 558A Manual PBX System
GL 72-06-1121972-06-19939.51 KBPBX Systems - 770A PBX New Features (Also EL 1927)
GL 72-06-1821972-06-2151.25 KBPBX Systems - Rerating of the 757A PBX (A&M) (Also EL 1943)
GL 72-11-0651972-11-1379.73 KBPBX Systems - 800A / 801A PBXs - No. 1 ESS CO Compatibility (Also EL 2129)
GL 77-12-0041977-12-02263.11 KBNumbering Plan for BSP Divisions 190, 201, 212, 215, 216, 218, 220, 226, 233, and 333
GL 78-02-0871978-02-161.18 MBDigital Channel Banks - Update and Summary of Modifications for Operation With No. 4ESS (Also EL 3451 and PL 2866 Supp. 2)
GL 78-05-0661978-05-10100.90 KBNo. 2 / 2B ESS - Call Hold Feature (Also EL 6109)
IL 79-11-2321979-11-16458.27 KBNo. 1/1A ESS - Right-To-Use (RTU) Fees for the 1E6 / 1AE6 Generic Programs (Also EL 6660)
IL 80-08-0781980-08-13170.03 KBNationwide Numbering Plan and Dialing Procedures - Replacement of the 903 NPA Code (Northwest Mexico) with the 706 Code
IL 80-08-0821980-08-1480.83 KBSwitching Systems - Routing Changes - Discontinuation of the Mis-Route Follow Up System (MRFUS)
IL 81-02-4381981-02-20432.39 KBDigital Channel Banks - Modifications for D1D, D2, and D3 to Increase Carrier Failure Delay Timing (Also EL 4246)
IL 87-03-0331987-03-20397.05 KBSplit of the 305 Numbering Plan Area (NPA) [Introduces 407 NPA in Florida]
IL 87-03-0451987-03-27527.11 KBSplit of the 303 Numbering Plan Area (NPA) [Introduces 719 NPA in Colorado]
IL 87-07-0031987-07-0251.28 KBSplit of the 617 Numbering Plan Area (NPA) [Introduces 508 NPA in Massachusetts]
IL 88-04-0151988-04-0847.04 KBSplit of the 312 Numbering Plan Area (NPA) [Introduces 708 NPA in Illinois]
IL 88-06-0121988-06-07325.46 KBNorth American Numbering and Dialing Plans [Announces dialing procedure changes in all California NPAs]
IL 89-02-0141989-02-0645.87 KBNANP - Interchangeable Central Office Codes in 404 NPA [Georgia]
IL 89-04-0281989-04-21449.37 KB1989 Numbering Plan Area (NPA) Code Split in Illinois [312 / 708]
IL 89-05-0381989-05-2654.31 KBNANP - Relief of the 214 Numbering Plan Area [903 NPA in Texas]
IL 89-09-0101989-09-0157.78 KBNANP - Split of the 201 Numbering Plan Area [908 NPA in New Jersey]
IL 89-10-0471989-10-1948.36 KBNANP - Interchangeable Central Office Codes in the Arizona 602 NPA
IL 89-10-0481989-10-1952.35 KBNANP - Interchangeable Central Office Codes in the Toronto, Ontario, Canada 416 NPA
IL 89-10-0491989-10-19112.34 KBNANP - Revised NPA Maps Showing New NPAs Scheduled to be Introduced in 1989 and 1990
IL 89-10-0721989-10-3151.74 KBNANP - Introduction of Interchangeable Central Office Codes in the 919 NPA [North Carolina]
IL 89-12-0221989-12-1358.42 KBNANP - Interchangeable Central Office Codes in the Michigan 313 NPA
IL 90-04-0011990-04-0349.29 KBNANP - Introduction of Interchangeable Central Office Codes in the 512 NPA [Texas]
IL 90-04-0021990-04-0349.58 KBNANP - Introduction of Interchangeable Central Office Codes in the 205 NPA [Alabama]
IL 90-04-0031990-04-0353.52 KBNANP - Introduction of Dialing Procedure Changes in the 202 and Portions of the 301 and 703 Numbering Plan Areas (NPAs) [Washington DC, Maryland, Virginia]
IL 90-06-0231990-06-1390.29 KBNANP - Revised Date for Split of 415 (California) Numbering Plan Area
IL 90-07-0041990-07-0948.20 KBNANP - Introduction of Interchangeable Central Office Codes in the 215 NPA [Pennsylvania]
IL 90-08-0521990-08-3156.74 KBNANP - Reminder of Numbering Plan Area (NPA) Code Splits in Texas and New Jersey
IL 90-08-0551990-08-3167.15 KBNANP - Split of 213 (California) Numbering Plan Area
IL 90-12-0491990-12-2871.64 KBNANP - Split of the 301 (Maryland) Numbering Plan Area (NPA)
IL 90-12-0501990-12-2842.77 KBNANP - Reminder of the February 1, 1991 Date for the Elimination of the Use of the 706 and 905 NPA Codes for Calls to Mexico
IL 91-01-0451991-01-2951.76 KBNANP - Introduction of Interchangeable Central Office Codes in the 205 NPA [Washington]
IL 91-02-0301991-02-14117.28 KBNANP - Revised NPA Map Showing New NPAs Scheduled To Be Introduced in 1991
IL 91-03-0091991-03-1248.46 KBNANP - Introduction of Interchangeable Central Office Codes in the 714 NPA [California]
IL 91-05-0281991-05-13129.65 KBIntegration of Public non-LEC ISDNs Into the North American Numbering Plan
IL 91-05-0351991-05-1752.56 KBNANP - Introduction of Interchangeable Central Office Codes in the Texas 713 NPA
IL 91-06-0441991-06-27121.03 KBNANP - Corrective Considerations for Elimination of Blocked Network Calls from Certain Customer Premises Equipment
IL 91-08-0011991-08-0177.65 KBNANP - Introduction of the 917 Numbering Plan Area (NPA) in New York City and Transfer of the Bronx, New York, From the 212 NPA to the 718 NPA
IL 91-08-0091991-08-07116.98 KBNANP - Revised NPA Map Showing New NPAs Scheduled To Be Introduced in 1992 and 1993
IL 91-10-0581991-10-3074.66 KBNANP - Split of the 404 Numbering Plan Area (NPA) and Dialing Procedure Changes in the 912 NPA in the State of Georgia
IL 92-01-0131992-01-061.22 MBNorth American Numbering Plan Administrator's Proposal On the Future of Numbering in World Zone 1
IL 92-02-0221992-02-1892.94 KBNANP - Split of 714 (California) Numbering Plan Area (NPA)
IL 92-03-06897.02 KBNANP - Split of 512 (South Texas) Numbering Plan Area (NPA)
IL 92-09-0461992-10-011.77 MBSplit of 416 (Ontario, Canada) Numbering Plan Area
IL 92-10-0171992-10-2067.92 KBFuture Work Plan: North American Number Plan Administrator's Proposal on the Future of Numbering in World Zone 1
IL 92-11-0221992-11-232.79 MBSplit of 313 (Michigan) Numbering Plan Area
IL 92-11-0241992-11-1396.97 KBSplit of 919 (North Carolina) Numbering Plan Area
IL 93-01-0011993-01-0590.03 KBNANP - Split of 215 (Pennsylvania) Numbering Plan Area (NPA)
IL 93-01-0081993-01-081.88 MBNorth American Numbering Plan Administrator's Proposal On the Future of Numbering in WZ1 - Second Edition
IL 93-01-0171993-01-133.43 MBStatus of Numbering Plan Area (NPA) Codes in World Zone 1
IL 93-04-0161993-04-09332.14 KBUpdated Information on the Georgia 404/706 Split and the California 714/909 Split
IL 93-04-0261993-04-1531.04 KBIntroduction of Service Access Code (SAC) 600 in Canada
IL 93-08-0021993-08-02118.79 KBAssignment of NPA Code "456" for International Carrier Identification
IL 94-01-0011994-01-03629.56 KBStatus of Numbering in the NANP Served Area
IL 94-01-0021994-01-0334.66 KBOpening of 710 Numbering Plan Area (NPA) Code
IL 94-01-0291994-01-21195.62 KBNANP - Split of 206 (Washington State) Numbering Plan Area (NPA)
IL 94-01-0301994-01-21207.56 KBNANP - Split of 602 (Arizona) Numbering Plan Area (NPA)
IL 94-01-0331994-01-2694.98 KBNANP - Split of 205 (Alabama) Numbering Plan Area (NPA)
IL 94-05-0041994-05-13115.67 KBApproval of 555 NXX Assignment Guidelines and Implementation Timeline
IL 94-05-0051994-05-19237.79 KBAssignment of SAC 500 for PCS
IL 94-08-0041994-08-09115.04 KBNANP - Overlay of 708 (Illinois) Numbering Plan Area (NPA)
IL 94-08-0051994-08-09102.08 KBNANP - Split of 703 (Virginia) Numbering Plan Area (NPA)
IL 94-08-0121994-08-19135.50 KBNANP - Overlay of 713 (Texas) Numbering Plan Area (NPA)
IL 94-09-0121994-09-21202.71 KBNANP - Split of 303 (Colorado) Numbering Plan Area (NPA)
IL 94-09-0131994-09-21116.51 KBNANP - Split of 813 (Florida) Numbering Plan Area (NPA)
IL 94-11-0141994-11-1625.86 KBReturn of 800-555 to the 800 SMS
IL 94-11-0161994-11-1646.41 KBNANP - Introduction of New 441 (Bermuda) Numbering Plan Area (NPA)
IL 94-11-0181994-11-2290.61 KBNANP - Split of 615 (Tennessee) Numbering Plan Area (NPA)
IL 94-12-0071994-12-2840.35 KBAssignment and Protection of Additional PCS NPA Codes
IL 94-12-0081994-12-2858.51 KBNANP - Overlay of 310 (California) Numbering Plan Area (NPA)
IL 95-01-0181995-01-311.03 MBNorth American Numbering Plan - Numbering Plan Area Codes - 1995 Update
IL 95-03-0021995-03-0842.77 KBNANP - Overlay of 214 (Texas) Numbering Plan Area (NPA)
IL 95-03-0061995-03-1491.04 KBNANP - Split of 803 (South Carolina) Numbering Plan Area (NPA)
IL 95-04-0021995-04-0679.77 KBNANP - Split of 203 (Connecticut) Numbering Plan Area (NPA)
IL 95-04-0071995-04-2133.78 KBNANP - Advance of 703 NPA (Virginia) Permissive Dialing Period
IL 95-05-0041995-05-0529.39 KBNANP - Extension of Permissive Dialing for 360 NPA (Washington State)
IL 95-05-0071995-05-19218.12 KBNANP - Split of 503 (Oregon) Numbering Plan Area (NPA)
IL 95-05-0101995-05-2524.71 KBNANP - Assignment of 888 NPA for Toll-Free Services
IL 95-06-0041995-06-08952.12 KBNANP - Status of Carrier Identification Code (CIC) Expansion
IL 95-06-0081995-06-222.01 MBNANP - Split of 404 (Georgia) Numbering Plan Area (NPA)
IL 95-07-0151995-07-27153.81 KBNANP - Split of 708 (Illinois) Numbering Plan Area (NPA)
IL 95-08-0071995-08-17289.98 KBNANP - Split of 604 (British Columbia) Numbering Plan Area (NPA)
IL 95-08-0111995-08-2377.31 KBNANP - Split of 305 (Florida) Numbering Plan Area (NPA)
IL 95-08-0151995-08-3190.68 KBNANP - Split of 314 (Missouri) Numbering Plan Area (NPA)
IL 95-09-0071995-09-15220.56 KBNANP - Split of 612 (Minnesota) Numbering Plan Area (NPA)
IL 95-09-0081995-09-27111.76 KBNANP - Split of 904 (Florida) Numbering Plan Area (NPA)
IL 95-11-0071995-11-1756.98 KBNANP Capacity Expansion Study by the INC
IL 95-11-0081995-11-17175.81 KBNANP - Split of 216 (Ohio) Numbering Plan Area (NPA)
IL 95-11-0091995-11-17113.27 KBNANP - Introduction of 242 (Bahamas) Numbering Plan Area (NPA)
IL 95-12-0051995-12-11112.72 KBNANP - Introduction of New 787 (Puerto RIco) Numbering Plan Area (NPA)
IL 95-12-0061995-12-1194.49 KBIntroduction of 246 (Barbados) Numbering Plan Area
IL 95-12-0071995-12-1146.67 KBNANP - Assignment of 880 and 881 NPAs for Inbound Foreign Billed Calls to Toll-Free Numbers
IL 96-01-0121996-01-25250.57 KBNANP - Split of 310 (California) Numbering Plan Area (NPA)
IL 96-01-0161996-01-01546.55 KBNorth American Numbering Plan - Numbering Plan Area Codes - 1996 Update
IL 96-01-0171996-01-30617.19 KBRevisions to the Split of 612 (Minnesota) Numbering Plan Area (NPA)
IL 96-02-0041996-02-08137.04 KBNANP - Split of 407 (Florida) Numbering Plan Area (NPA)
IL 96-02-0131996-02-29181.99 KBNANP - Split of 804 (Virginia) Numbering Plan Area (NPA)
IL 96-02-0141996-02-29105.40 KBNANP - Split of 312 (Illinois) Numbering Plan Area (NPA)
IL 96-03-0051996-03-26108.06 KBNANP - Introduction of New 268 (Antigua & Barbuda) Numbering Plan Area (NPA)
IL 96-04-0091996-04-22464.23 KBNANP - Split of 619 (California) Numbering Plan Area (NPA)
IL 96-04-0101996-04-22127.26 KBNANP - Introduction of New 664 (Montserrat) Numbering Plan Area (NPA)
IL 96-04-01475.03 KBNANP - Introduction of New 758 (St. Lucia) Numbering Plan Area (NPA)
IL 96-04-0161996-04-30178.04 KBDesignation of Universal IntraLATA Presubscribed Carrier Verification Number
IL 96-06-0011996-06-04101.89 KBNANP - Introduction of New 868 (Trinidad & Tobago) Numbering Plan Area (NPA)
IL 96-06-0081996-06-2175.98 KBNANP - Overlay of 410 (Maryland) Numbering Plan Area (NPA)
IL 96-06-0091996-06-2172.15 KBNANP - Overlay of 301 (Maryland) Numbering Plan Area (NPA)
IL 96-06-0111996-06-28248.19 KBNANP - Split of 513 (Ohio) Numbering Plan Area (NPA)
IL 96-07-0041996-07-1755.22 KBCorrection to 301 NPA (Maryland) Relief Plan Contact Information
MM 48-130-101948-05-2886.43 KBTerminology for Semiconductor Triodes - Committee Recommendations - Case 38139-8
MM 54-2433-31954-01-299.59 MBMessage Circuit Noise Objectives - Distribution Curves of Bell System Values and Relation to British Post Office Objectives - Files 36725-1 and 38925-28
MM 55-2433-61955-06-0241.20 MBCoordination Requirements for Single Frequency Interferences Between Type P1 and Various Toll Carrier Systems - File 36675-9
MM 67-2623-21967-02-012.50 MBActive RC-Tantalum Integrated Circuit Filter Design for High Performance Specifications - Part I
MM 67-2655-111967-05-031.07 MBAn Electromechanical Filter Below 500 Hz
MM 67-4734-71967-05-152.54 MBAn Introduction to the Available Programs and Other Design Aids for the Design of Filters, Equalizers and Other Networks
MM 67-5311-181967-08-291.27 MBNotes on the Design of Cosine Roll-Off Filters
MM 67-5316-11967-01-039.19 MBActive RC Filter Building Blocks Using Frequency Emphasizing Networks Part I
MM 67-5316-31967-05-152.95 MBRealization of FEN RC Input Networks
MM 67-5316-61967-09-146.92 MBDesign of a Modified Raised Cosine Filter Using Hybrid Integrated Filter Sections
MM 67-6323-61967-04-041.75 MBDesign Considerations for 50 dB Bandpass Filter
PEL 69161961-12-206.07 MBPBX Systems - New Attendant's Consoles
PEL 69761962-04-1310.04 MBSwitching System No. 400 (20-40 DIAL PBX)
PEL 70711962-11-07282.22 KBPBX System - 756A PBX - Direct Station Selection (DSS) from Stations
PEL 71251963-03-183.20 MBPBX Systems - 701PK and 711PK PBX Systems
PEM 58341955-12-1377.26 KBPBX Systems - Multi-Plug Patching Cords for Night Connections
PEM 79561962-05-08122.76 KBPBX Systems - New Code Series for PBX Consoles
PEM 81331962-10-2288.22 KBStation Apparatus - Plug-Ended D50P Cord For Use With 6050-Series Keys
PEM 81401962-11-01117.62 KBStation, PBX and Common Systems - 34A KTU and Trunk Make-Busy Control Key Arrangements
PEM 82071963-01-14170.75 KBStation Systems - 249A and 250A Key Telephone Units