from 1992 ISDN on an AT&T 5ESS ~~~~~~~~~~~~~~~~~~~~ Basic ISDN Information ~~~~~~~~~~~~~~~~~~~~~~ Integrated Services Digital Network (ISDN) is a service that provides digital transmission of voice/data, simultaneously, over a single cable pair. This line extends from the servicing telephone Central Office (CO) to the customer's premises. An ISDN line provides three channels or transmission paths. Two of the channels are called "B" or Bearer channels, and the third is called a "D" or Signalling channel. The B channels are capable of transmitting 64 kilobits per second (Kbps) each, and the D channel 16 Kbps for a total circuit rate of 144 Kbps. This ISDN type is referred to as 2B+D and is identified as Basic Rate Access ISDN (BRI). Each B channel is capable of: The D channel is capable of: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - Circuit switched voice - Signalling - Circuit switched data - Packet switch data - Packet switched data The D channel acts as a controller, transmitting digital messages from the Customer's Premises Equipment (CPE) to the central office switch to carry out the various functions as requested by the customer. In addition to its signalling capabilities, the D channel also can transmit customer data in a packet format but at a lower speed than that of the B channels. Digital telephones are used on ISDN line. The digital telephone, also known as a "Voice Terminal", provides key system features and also allows a computer to be connected to the line. An analog telephone can be used on an ISDN line, but it must be connected via a Terminal Adapter (TA) to convert the digital signal to its analog equivalent. An ISDN line is separated by different interfaces (points of reference). The interfaces are accepted "international standards" and define wiring schemes, connection points, CPE and network functions, and transmission/electrical standards. The "U" interface (2 wire) extends from the ISDN CO switch to the Network Termination (NT1). The "T" interface (4 wire) extends from the NT1 to the ISDN CPE. +---------+ +---------+ +-------------+ +------------+ | ISDN | | Network | | Network | | ISDN | | Digital |=========| Inter- |======| Termination |===| Telephone, | | Switch | | face | | (NT1) | | Computer | +---------+ +---------+ +-------------+ +------------+ ^ ^ ^ T Interface ^ | U interface (2 wire) | | (4 wire) | +-----------------------------------+ + ------------- + Basic Rate ISDN (BRI) can be either point to point (a line with one work station ) or it can be multi-point (a line with several work stations). Point to Point ISDN Line ~~~~~~~~~~~~~~~~~~~~~~~~ Regulated ! Non-Regulated ! ! +---------+ +---------+ IW +-------------+ IW +------------+ | ISDN | | Network | | Network | | ISDN | | Digital |=====| Inter- |========| Termination |========| Telephone, | | Switch | | face | | (NT1) | | Computer | +---------+ +---------+ 2 wire +-------------+ 4 wire +------------+ 2 wire ! ^ ^ ! | CPE | ! +-----------------------------------+ IW = Inside Wiring Multi-Point ISDN Line ~~~~~~~~~~~~~~~~~~~~~ Multi-point service allows a maximum of eight ISDN devices to share a single ISDN line. In Ameritech tariff, only two of these devices may be provisioned as B channel devices. B channel devices will support Circuit Switched Voice (CSV) applications, i.e. Electronic Key Sets or Circuit Switched Data (CSD). The remaining six of the allowable eight devices must be D channel packet devices. Multi-point ISDN service is available to customers served by an AT&T 5ESS Central Office with the 5E5 or higher generic. Not all ISDN CPE is compatible with a multi-point application. Guidelines for terminal usage are listed as follows: Base Initializing Terminals (BITS): BITS do not work on a multi-point ISDN line. In the case of AT&T CPE, these terminals are designated as Feature Package 1 (FP1). Likely examples of these types of terminals are those associated with the 650X series type terminals NON - Initializing Terminals (NITS): NITS work on multi-point lines, but have a limited feature set. Fully Initializing Terminals (FITS): FITS work on a multi-point line with full feature set. AT&T sets have the full feature sets available in Feature Package 2 (FP2) To summarize, customers requesting ISDN multi-point BRI lines must have devices that function as a NIT or FIT. Service Profile Identification (SPID) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Since multi-point ISDN lines will have several ISDN terminal devices assigned to them, there has to be a way for the CO to identify each terminal. The SPID number gives each terminal device a unique identifier other than the assigned telephone number. The SPID must be programmed into each device before dial tone can be obtained. Generally this function is performed by the customer's vendor. However, if the customer requests that a Ameritech technician perform this task all time expended will be reported to and billed as non regulated. A SPID is made up of the following components: 0 1 2 2 2 2 3 4 1 0 Is the SPID for Circuit TN 222-2341 t p N N N X X X X 0 ^ ^ ^ ^ | | | | | | +--------------------+---> Characters 3-8 represent the Extended | | Primary Directory Number + 0 | | | +---------------------------> Second character indicates the | Numbering Plan Identifier (NPID) | | 1 = Circuit TN | 3 = Packet TN | | +------------------------------> First character indicates the Network Address Type 0 = TN 1 = MLHG/TN (Multi-Line Hunt Group) Elements of a BRI multi-point ISDN Line, starting from the T interface: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +-------------+ | |===========================> Device #8 - ISDN Voice Terminal | |===========================> Device #7 | NT1 |===========================> Device #6 | 8 Jack |===========================> Device #5 | 8 Pin |===========================> Device #4 | multiple |===========================> Device #3 | 367A Block |===========================> Device #2 | |===========================> Device #1 - ISDN Computer TA +-------------+ Multi-Point Limitations ----------------------- 8 Terminals, maximum 2 CSV/CSD terminals active simultaneously 1-8 D Channel terminals ISDN Loop Qualifications ~~~~~~~~~~~~~~~~~~~~~~~~ Copper loops must be checked for conformance when deploying ISDN service. Marketing will request a loop qualification survey prior to selling ISDN service. The Outside Plant Engineer (OSPE) will determine if cable facilities can support the service. Distribution Services Field technicians may be requested by OSPE to perform transmission tests on the facilities if the plant records do not provide conclusive qualification information or the loop borders on marginal qualification. Field technician loop testing procedures are discussed later in this document. Transmission Requirements - CO to NT1 (U Interface) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2B1Q Requirements for all types of switches ------------------------------------------- (All of Ameritech central office's use the 2B1Q line code.) 2B1Q = Two Binary Bits and One Quaternary symbol representing 4 voltage amplitudes or line code The transmission requirements for an ISDN 2B1Q BRI is illustrated below: Central Office MDF Customer Premises +---------+------+ Frame !~! +-----+ +-----+ | ISDN | U | Wiring ! ! 2 wires | | IW | | | SWITCH | Line |==========! !=================| SNI |=========| NT1 | | | Card | assume ! ! | | assume | | | | | 250 Ft. ! ! +-----+ 500 Ft. +-----+ +---------+------+ ~ ^ ^ | | -42 dB at 40 kHz (135 Ohm Impedance) | +----------------------------------------------+ Loop requirements for ISDN are as follows: 1) Load coils, build-out capacitors and bridge lifters are NOT allowed. 2) Maximum transmission loss allowed is: -42 dB at 40 kHz with 135 ohm impedance from CO U line card to the NT1 Assumes 250 Ft. of CO wiring and 500 Ft. customer premises wiring unless otherwise known. 3) Bridged tap loss must be included in overall loop loss. Bridge tap in the feeder must be identified by length. Use a loss figure of 1.7 dB per kilo feet per bridged tap. The maximum allowable loss of a single bridged tap is 5.1 dB regardless of length. The following chart describes transmission loss of 2B1Q lines: Cable Loss Constants in dB/KFt at 40 kHz, 135 Ohm Impedance ----------------------------------------------------------- PIC Cable Temperature (F) PULP Cable Temperature (F) 68 90 120 68 90 120 Cable Gauge UG BUR AIR UG BUR AIR ------------------------------------------------------------------------------- 19 0.762 0.791 0.829 0.839 0.869 0.910 22 1.296 1.349 1.420 1.382 1.436 1.510 24 1.874 1.945 2.040 1.960 2.032 2.129 26 2.663 2.757 2.880 2.667 2.760 2.882 ------------------------------------------------------------------------------- The following is an example of how the Loss Constants Chart can be used to determine the loss for each section of the loop: CO Wire = 0.25 KFt x 1.874 (24 ga.) = 0.47 dB FDR Loop = 7.25 KFt x 2.667 (26 ga.) = 19.35 dB FDR BT #1 = 4.00 KFt x 1.700 (5.1 max) = 5.10 dB FDR BT #2 = 0.50 KFt x 1.700 (5.1 max) = 0.75 dB Dist Loop = 4.00 KFt x 2.040 (24 ga.) = 8.16 dB Dist BT = 1.50 KFt x 1.700 (5.1 max) = 2.55 dB Cust. Wiring = 0.50 KFt x 1.874 (24 ga.) = 0.94 dB -------- -------- 18.00 Kft 36.48 dB NOTE: To calculate frame and customer interior wiring loss, use the UG temperature and 24 gauge. Central Office Wiring Qualification ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ A loss requirement (-42 dB for 2B1Q) is on the entire loop. Assume that there will be 250 feet of frame wiring. When the limitation for frame wire loss must be determined use the Loss Constants Chart above. Premises Wiring Qualification (U Interface) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ A loss requirement (-42 dB for 2B1Q) is on the entire loop. Assume that there will be 500 feet of customer wiring. When the limitation for customer premises interior wiring must be determined use the Loss Constants Chart above. IMPORTANT: If Ameritech is requested to install the interior wiring, twisted pair should be used. If Ameritech is not installing the interior wiring, the customer's vendor should ensure that the wiring meets the loss requirements. Ameritech can test the wiring for transmission loss, but should bill the customer at de-regulated time sensitive charges. Provisioning - ISDN ~~~~~~~~~~~~~~~~~~~ Recent Change Center -------------------- RCC will input the translations using manual Centrex forms prepared by Marketing. Outside Plant Engineer ---------------------- The OSPE will reserve the qualified ISDN pairs and inform Cutover to assign the loaded pair indicator of "B". Mechanized Assignment Center ---------------------------- The MAC center will manually assign the pre-qualified cable facilities that were reserved by the OSPE. These pairs will be identified by the loaded pair indicator of "B". DSOC Load Area -------------- the DSOC load area should identify all ISDN service orders by the USOC "WTQAD". These service orders should be sent to the Field Supervisor upon receipt so that he/she can pre-survey the job. Field Supervisor ---------------- The Field Supervisor should contact the customer and make an appointment to pre-survey. During the pre-survey, the supervisor should determine the start date of perform pre-installation tests and network interfacing. Arrangements should be made for transmission testing of cable facilities from the CO Main Distribution Frame (MDF) to the customer's Network Interface (NI). Coordination procedures with vendor should also be arranged. Field Technician ---------------- The Field Technician should install the appropriate network interface, as noted on the service order, and label with the phone number. The following "pre-installation" tests should be performed prior to the due date: 1) FAULTS - Loop should be clear of faults (TOK with Mechanized Loop Test MLT shoe test). An UNBALANCE or a CROSS has a severe impact on ISDN service. Test Equipment: KS 8455 test set or equivalent. MLT may also be used. 2) LOOP LOSS - Maximum loss from the CO line card to the network interface is -42 dB at 40 kHz with a 135 ohm termination impedance for a line served by 2B1Q line code. Test Equipment: Hewlett Packard Model 4935 TIMS or equivalent. When the CO wiring and transmissions have been completed, the ISDN line can be tested with the Tektronics Craftek CT-100 test set to determine polarity, ceiling current, synchronization, and line origination/termination functions. Maintenance - ISDN ~~~~~~~~~~~~~~~~~~ Repair Answer ------------- CRSAB/MBA will answer repair calls for ISDN customers. The RSA will obtain the Primary Directory Number (PDN) of the ISDN line, description of trouble, callback name and telephone number. The trouble will be sent to the appropriate DSOC/Major Account Center via Loop Maintenance Operating System (LMOS). DSOC/Major Account Center -------------------------- The MA/COT will determine if the trouble is related to line or feature translations or operation. The RCC may be required to verify translations until such time that MAs can be trained. If line/feature translations or operation is correct, the ISDN line must be tested. The ISDN line can be tested by the MA/COT using MLT-ISDN to run diagnostic tests (as long as LMOS line record is built properly). This test can determine whether the trouble is in or out. In some cases (when MLT-ISDN doesn't work) it may be necessary to have the Switch Control Center (SCC) perform a digital loop back test by accessing the ISDN switch. This test can also determine whether the trouble is in or out. If the MLT-ISDN test determines that a dispatch is required to troubleshoot a loop fault, the trouble will be dispatched to an ISDN trained and equipped Field Technician. In some cases after dispatch, and the technician is unable to resolve the problem, a MA/COT may need to escalate troubles for Tier 1 support if the line passes Tektronics testing but CPE does not function properly. The SCC contact numbers for Tier 1 support are: Appleton - 920-832-1994 Madison - 608-252-2601 Milwaukee - 414-678-3606 Field Technician ---------------- The Field Technician will isolate and fix loop fault problems. If the Field Technician has repaired the loop fault or not found a loop fault, and the line is still not working properly, the Tektronics test set can be utilized to determine if the customer's CPE and/or interior wiring is operating properly. The Tektronics test set can simulate an NT1 and an ISDN voice terminal. If the Tektronics test set indicates frame errors when testing from the NI, loop transmission tests should be performed with the Hewlett Packard 4935A to ensure that the facility can transmit the ISDN digital signal with no errors. Inside wire transmission/fault testing can also be performed to determine frame error trouble source. Charges apply if interior wiring is repaired or does not meet transmission standards unless customer is on a maintenance plan. If the ISDN line passes all Tektronics tests, but the customer's service is not working properly, i.e. voice ok, but can't transmit from computer, the trouble should be escalated to the SSC and DATRAN. Distribution Services is still maintenance control of the trouble and must track progress with escalation groups. The customer should be kept informed of the trouble progress. Service Compatibility ~~~~~~~~~~~~~~~~~~~~~ The compatibility of ISDN and other voice/data services in the same cable sheath or binder group is governed by the degree of electromagnetic coupling of the services signal from its pair of wires to another pair. This condition is called crosstalk, which is familiar to us with POTS service. A major factor in reducing or eliminating crosstalk is to limit the loop length or distance to the potential customer. Another factor is the power level or signal strength. The most common crosstalk situation occurs when an analog and digital service exist on the same cable or binder group. The ultimate resolution may involve moving the disturbed or disturbing service to a different binder or sheath in order to eliminate a crosstalk condition. Analyzing these troubles will not be easy. Please request assistance from Loop Support Staff. Cable Transfer Activity ~~~~~~~~~~~~~~~~~~~~~~~ Cable pair rearrangements on ISDN service should be avoided, but if necessary, loop transmission testing must be done on the new facilities before the transfer work to ensure continuity of the service and customer satisfaction. Remember that ISDN lines are identified in MAC with a loaded pair indicator of "B" CTAP procedures for ISDN service: 1) The new facilities can not be loaded and only minimal bridge tap is allowed 2) Loop Qualification tests must be done prior to the transfer work to ensure that the pairs meet the required parameters. 3) The transfer work must be done with no half tapping. 4) The transfer work MUST be included in the CTAP schedule, i.e. customer must be notified before cutting to the new facility. 5) The cutover test person must test the service with the customer after cutting to the new facilities. Ensure that both voice and data service is working properly. Appendix ~~~~~~~~ Service Order USOC Definitions ------------------------------ USOC Description ~~~~ ~~~~~~~~~~~ WTQAD Primary Directory Number (includes 3 appearance of PN on Terminal) FGD Secondary Directory Number N2Q 2 Wire, Basic Rate, U Interface, 2B1Q N4Q 4 Wire, Basic Rate, T Interface, 2B1Q S2Y 2 Wire, Basic Rate, U Interface, AMI S4Y 4 Wire, Basic Rate, T Interface, AMI LTQ1X Alternate Voice and Data (B Channel) LTQ3X Packet Switched Data (B Channel) LTQ4X Packet Switched Data (D Channel) LTQ5X Circuit Switched Voice (B Channel) LTQ6X Circuit Switched Data (B Channel) ACSIX Multiple Call Appearances (MCA) or Primary Directory Number D08 Shared Primary or Secondary (SCA) Directory Number Service Order Examples ~~~~~~~~~~~~~~~~~~~~~~ The following is an example of an ISDN service order (point to point), installing a new ISDN line with Circuit Switched Voice (CSV) on one B channel and Packet Switched Data (PSD) on the D channel: ---S&E RGB 1 I1 WTQAD/CX XXXX/PIC XXXC/RES XX/DES TERM ON A 7505 SET, CONFIG GROUP WB750701 I1 N2Q/CX XXXX I1 LTQ5X/CX XXXX I1 LTQ4X/CX XXXX I1 9ZR/CX XXXX I1 XXX/CX XXXX I1 XXX/CX XXXX I1 XXX/CX XXXX NOTE - WTQAD Designates this as an ISDN service N2Q Designates this line code as 2B1Q, U Interface CX XXXX Identifies the Centrex number (extension) LTQ4X Identifies Packet Switched Data (D Channel) LTQ5X Identifies Circuit Switched Data (B Channel) Other USOCs (XXXXX/CXXXX) generally designate optional Centrex features, billing, plans, etc. The following is an example of an ISDN service order (point to point), installing two new ISDN lines with Circuit Switched Voice (CSV) on one B channel and Shared Call Appearance (SCA) of a primary or secondary number: ---S&E RGB 1 I1 WTQAD/CX 2222/PIC XXXC/RES XX/DES TERM ON A 7505 SET, CONFIG GROUP WB750701 I1 N2Q/CX XXXX I1 LTQ5X/CX 2222 I3 D08/CX XXXX I1 9ZR/CX XXXX I1 XXX/CX XXXX I1 XXX/CX XXXX I1 WTQAD/CX 3333/PIC XXXC/RES XX/DES TERM ON A 7505 SET, CONFIG GROUP WB750701 I1 N2Q/CX XXXX I1 LTQ5X/CX 3333 I3 D08/CX XXXX I1 9ZR/CX XXXX I1 XXX/CX XXXX I1 XXX/CX XXXX NOTE - WTQAD Designates this as an ISDN service N2Q Designates this line code as 2B1Q, U Interface CX XXXX Identifies the Centrex number (extension) LTQ5X Identifies Circuit Switched Voice (B Channel) I3 D08/CX XXXX Identifies the quantity of SCAs Other USOCs (XXXXX/CXXXX) generally designate optional Centrex features, billing, plans, etc. The following is an example of an ISDN service order for multi-point ISDN service. Installing one new ISDN line with two primary numbers, each with Circuit Switched Voice (CSV) on a B channel: ---S&E RGB 1 I1 WTQAD/CX 9888/PIC XXXC/RES XX/DES TERM ON FUJITSU SRS 1050, MULTIPOINT WITH 608 264-6931, CONFIG GROUP 03105001 I1 N2Q/CX 9888/DES ASSIGN LEN, MULTIPOINT WITH 608 264-6931 I1 LTQ5X/CX 9888/DES MULTIPOINT WITH 608 264-6931 I1 TJVDF/CX 9888 I1 E6GDF/CX 9888/CFN 266-8040 I1 9ZR/CX 9888 I1 XXX/CX 9888 I1 XXX/CX 9888 I1 WTQAD/CX 264-6931/PIC XXXC/RTE NONE/RES XX/DES TERM ON FUJITSU SRS 1050, MULTIPOINT WITH 608 266-9888, CONFIG GROUP 03105001 I1 N2Q/CX 264-6931/RTE NONE/DES DO NOT ASSIGN LEN, USE LEN ASSIGNED TO 266-9888, MULTIPOINT WITH 608 266-9888 I1 LTQ5X/CX 264-6931/DES MULTIPOINT ITH 608 266-9888 I1 TJVDF/CX 264-6931 I1 9ZR/CX 264-6931/RTE NONE I1 XXX/CX 264-6931 I1 XXX/CX 264-6931 NOTE - WTQAD Designates both numbers as ISDN service, trailing info identifies multi-point service and the second number associated with this line. N2Q Designates this line codes as 2B1Q (U interface), also trailing info identifies multi-point service. CX XXXX Identifies the Centrex number (extension) LTQ5X Identifies Circuit Switched Voice (B Channel), also trailing identifies multi-point service. Other USOCs (XXXXX/CXXXX) generally designate optional Centrex features, billing, plans, etc. The following is an example of a MAC field work ticket for point to point and multi-point ISDN: MAC Field Work Tickets ---------------------- The ICKT identifies the ISDN line and the PN is the Primary Directory Number associated with that line. Point to Point ~~~~~~~~~~~~~~ 11/19/92 FIELD WORK TICKET 000096 PAGE 0001 ORD N4146780793 DD 12-15-92 PTD NPA: 414 NNX:341 ---ASGM ICKT 55.IBSQ.1234..WT/ISDN ISDN PN 341-0002 RT 3126 /RZ 13 IPTY 1 IF1 /CA 00048/PR 2149/TEA IN 625 N WATER ST;PDW /BP 2149 RMTE PROTECTED END Multi-Point (service will reflect several PNs on one line) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 11/19/92 FIELD WORK TICKET 000094 PAGE 0001 ORD N4146780790 DD 12-15-92 PTD NPA: 414 NNX:341 ---ASGM ICKT 55.IBSQ.1234..WT/ISDN ISDN PN 341-0003 and 341-0004 RT 3126 /RZ 13 IPTY 1 IF1 /CA 00048/PR 2149/TEA IN 625 N WATER ST;PDW /BP 2149 RMTE PROTECTED END Craft Access Screens ~~~~~~~~~~~~~~~~~~~~ CUST INFO SECTION Note: Customer Info section, screen 3/8 reflects the ISDN and 1DQ service code and class of service, screen 8/8 reflects the LMOS message "ISDN" in the FI field. |4145551212 |AMERITECH |REVIEW to see mail |address: 2/8 |722 N BROADWAY |MILWAUKEE | 3/8 | | |ISDN 1DQ | 7/8 |route: 999 123 4567 |rec: 03-30-92 0900 A |cust at 4145551111 |FI: 8/8 | |ISDN | TRBL INFO SECTION Note: Trouble Info section, screen 4/7 reflects the initial test results of "ISDN NT1 Term" |initial test: 4/7 |ISDN-NT1 TERM | | |Access:A0100P 5/7 |B0500P | | |last trouble 6/7 |cleared: 03-01-92 | | Overall ~~~~~~~ Overall ISDN is just a way for phone companies to sell extra signalling trunks to unsuspecting customers then rip them off for thousands. Don't fall for it.