AIS - Automatic Intercept System INTRODUCTION... ~~~~~~~~~~~~~~~ Computer Consoles Incorporated (CCI) manufactures various hardware appliances to be used in conjunction with phone companies switches as well as other aspects of the companies' uses, plus computer systems such as their own Unix-supporting systems. DAIS II is the Distributed Automatic Intercept System, which is the system used to announce if the subscriber has dialed a non-working number. This is what you hear, in action, when you dial a wrong number and get the 3 tones plus the announcement or the ONI (Operator Number Identification) intercept operator ("What number did you dial?"). The information from this file comes mostly from an instructional manual sent to me by CCI, who can be reached at 800-833-7477 or 716-482-5000 directly, or may be written to at 97 Humbolt Street, Rochester, NY, 14609. INTERCEPTION ~~~~~~~~~~~~ Most definitely any person who has used a telephone in his life has, by some means or another, come across the dreaded 3 tones, leading up to the ever-so-cumbersome announcement telling of the disconnected or non-working number. This file will go into how the whole system works. After dialing the non-working number, the telco's Class 5 End Office routes the call to DAIS II. ANI Calls ~~~~~~~~~ Provided that the End Office has Automatic Number Identification (ANI) equipment, the equipment then identifies the digits of the called number and sends them to the intercept system. The system receives the called number from the end office, retrieves information for that number from the intercept database, formulates the message, and delivers it to the customer in an automated announcement. These announcements can either be standardized or tailored to the independent telephone companies' needs. If further assistance is required, the caller can then stay on the line and wait for an operator to come onto the line. ONI Calls ~~~~~~~~~ When the End Office is primitive, and they don't have the ANI equipment to do the above ritual, operators are directly involved. These operators are also called into action when there is an ANI or DAIS II failure. When the ONI (Operator Number Identification) call comes in, DAIS II routes the call to the operator. The operator asks for the number that the customer called and then keys it into her KDT (Keyboard Display Terminal). After she hits the command key, the number's information is searched for in the intercept database, the message is formulated, and the automated response is announced. Once again, if the caller needs further assistance, an operator will return to the line to help the subscriber. Operators will return to the line for any number of reasons. They include the following: Unsuccessful Searches - After DAIS II receives the called number from ANI equipment or from an operator, it searches the database to find the intercept message associated with the telephone number. The database contains all 10,000 line numbers for each exchange in the calling area. If the system cannot complete the search, the number was either keyed in incorrectly or there is a problem in the system. The call is then routed to an operator and displays the intercepted number (including NPA) on the KDT screen along with a message indicating why the search could not be completed. If the number was keyed in wrong, the operator will correct the number, or else she will ask the subscriber to re-dial the number. Aborted Announcements - If a search is given successful but for one reason or another the automated announcement cannot be given, the call is routed to an operator. The KDT display shows the intercepted number, the appropriate information for a verbal response, and the message, "VERBAL REPORT." In this case, the operator quotes the message to the caller rather than activating the automated response. Reconnects - If a customer remains on the line for more information after receiving the automated announcement, the system routes the call to an operator. The operator's KDT display shows the called number plus other pertinent information given to the caller in the previous announcement. From here, the operator can respond verbally to the customer's needs, or activate the automated system again. The DAIS II system allows up to 4 reconnects per call, but the possible number of reconnects available ranges from 0-3. With 1 reconnect, the operator must report verbally. Split Referrals - If a number has been changed but replaced with two numbers, this is called a "split referral." When the database finds 2 or more numbers, the DAIS II system routes the customer to an operator, displaying the old number and new listings on the KDT screen. The operator then asks which number they are looking for and keys in the command key to activate the announcement, or else they do the announcement verbally. Operator Searches ~~~~~~~~~~~~~~~~~ Situations may arise where the subscriber needs more information than was given by the automated announcement, or believes the information to be invalid. DAIS II provides for operators to have access to both the intercept and the DA databases at all times as long as the system administrator, who judges the extent to which operators can use the cross-search capability, allows it. Components Of The System ~~~~~~~~~~~~~~~~~~~~~~~~ The telco's Class 5 End Offices contain switching equipment that routes calls to DAIS II. If the office has ANI equipment, the switch routes the called digits to the intercept system in the form of multi-frequency tones. The end offices route calls to DAIS II on dedicated (direct) trunks. These direct trunks can carry ANI traffic or ONI traffic, but not both. If trunk concentrators are used, the concentrator trunks to DAIS II may carry ANI calls, ONI calls, or both, depending on the types of trunks coming into the concentrators from the end offices. The call is identified as ANI or ONI through MF tones transmitted by the concentrators. If an operator must be involved (due to ONI or further assistance), DAIS II routes the call to the telco's ACD (Automatic Call Distributor), which is a switching device that routes calls to any available operator. The intercept data base resides on disk in the ARS (Audio Response System). ARS processors known as Audio Response Controllers (ARCs) search the intercept database. If a call requires an operator's services, the Marker Decoder Unit (MDU) provides ACD routing information to the ARC. The DAIS II Automatic Intercept Communications Controllers (AICCs) route messages between the ARCs and the DAIS II subsystems. An intercept subsystem that is housed at the same location as the database is called a Colocated Automated Intercept System (CAIS). A subsystem located at a distance from the database is known as a Local Automated Intercept System (LAIS). Each subsystem can provide automated announcements without using expensive trunking to route ANI calls to a centralized intercept office. Only calls that require operator assistance are routed on trunks to the ARS site. Because those trunks are only held white the operator identifies the number and are released before the announcement begins, trunk requirements are reduced. The automated announcement is always given by the intercept subsystem. Each CAIS or LAIS site contains a Trunk Time Switch (TTS) and DAIS II Audio Response Units (DARUs). Intercept trunks from the concentrators and the Class 5 End Offices terminate at the TTS. When an ONI call comes in on one of these trunks, the TTS routes it to the ACD. When an ANI call comes in, the TTS routes the called number to the ARC. After the ARC retrieves the appropriate message from the database, it sends that information back to the TTS, which connects a DARU port to the trunk on which the call came in. Then, the DARU produces an automated announcement of the message and delivers it to the caller. ARS hardware generates only DA announcements whereas DAIS II hardware generates only intercept announcements. Automatic Intercept Communications Controller (AICC) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The AICC routes messages between the ARC and the TTS. Two units are required to enhance system reliability. Each pair of AICCs can communicate with up to 4 CAIS or LAIS subsystems. The AICCs are similar to the Audio Communications Controllers (ACCs) in the ARS system, but AICCs use a Bisynchronous Communications Module (BSCM) instead of a LACIM. An AICC can be equipped with up to 8 BSCMs, each of which handles one synchronous communication line to the TTS. The BSCM models selected depend on the location of the AICC with respect to the CAIS/LAIS sites. Standard SLIMs (Subscriber Line Interface Modules) are required for communication with the ARC. Trunk Time Switch (TTS) ~~~~~~~~~~~~~~~~~~~~~~~ The TTS has two types of components: the Peripheral Modules (PMs) and the Common Controls (CCs). The PM contains the printed circuit boards that provide the link between the end office's ANI trunks and the ARC and between the ONI trunks and the ACD. The activity of the PM is under direction of the CC A PM rack contains five types of circuit boards: Multi-frequency Receivers (MFRs), Analog Line Front Ends (ALFEs), T1 Front Ends (T1FEs), Peripheral Module Access Controllers (PMACs), and Multi-purpose Peripheral Devices (MPPDs). The MFRs translate the intercepted number from multi-frequency tones to ASCII digits for ANI calls; for ONI calls that come through a trunk concentrator, the MFRs translate the tones sent by the concentrator to indicate an ONI call. Based on the tones, the MFR determines the type of call: regular, trouble, etc. ALFEs convert incoming analog data to digital form so that it can be switched on the digital network. They also convert outgoing digital data back to analog. Incoming ALFEs provide the link between the TTS and the analog trunks from the Class 5 End Offices. Outgoing ALFEs provide the link between the TTS and the analog trunks to the ACD. ALFE is subdivided into two types for both incoming and outgoing: ALFE-A (contains the control logic, PCM bus termination, and ports for 8 trunks) and ALFE-B (contains ports for 16 trunks, but must be paired with an ALFE-A in order to use the control logic and PCM bus on the backplane). ALFE-As can be used without ALFE-Bs, but not vice versa. Incoming ALFEs support E&M 2-wire, E&M 4-wire, reverse battery, and 3-way signalling trunks. Outgoing ALFEs support E&M 2-wire, reverse battery, and high-low trunking. T1FEs provide the links between the TTS and the D3-type T1 spans from the end offices. They also link the DARU VOCAL board ports and the TTS. Each board has 24 ports in order to handle a single T1 span which carries 24 voice channels. PMAC is based on a Motorola 68000 microprocessor that directs and coordinates data flow within the PM. MPPD boards provide bus termination and the system clocks for the digital network. The MPPD contains a master and a secondary clock, which are synchronized with the frequency of an incoming T-1 span. The module also contains its own clock for use when T-1 synchronization is not available or lost. The MPPD also generates the ringing tones, busy signals, and reorder tones heard by the customer and sends the zip (alert) tone to the operator. The CC controls the interaction between the PM components and the DARU. It contains the Office Dependent Data Base (ODDB), which is a system table that describes the configuration of the TTS. The CC uses the ODDB to determine whether an incoming call is an ANI or ONI trunk. The CC sets up paths through the digital network in order to coordinate the resources of the CAIS/LAIS. It receives messages from the PMAC, stores information necessary for returning a response to the appropriate trunk, and controls message routing to and from the ARC or the operator. It also synchronizes the TTS and the Directory Assistance System (DAS) for operator-caller communications. The CC is a Power-series standalone processor that contains a central processing unit (CPU-2), based on the Motorola 68000 microprocessor. The processor also contains distributed intelligence for controlling the memory subsystem, the IO (input/output) subsystem, and the disk/tape subsystem. Each CC includes a Winchester disk drive, a quarter-inch tape drive, and additional miscellaneous hardware. DAIS II Audio Response Unit (DARU) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The DARU contains the VOCAL boards that produce automated announcements, which are compiled from a vocabulary stored in RAM. A CAIS/LAIS contains 1 to 3 DARUs, each with 48 ports. If a CAIS/LAIS houses more than one DARU, the units are multi-dropped together. One DARU is always linked to the ARCs (either directly or by modems and telephone lines) so that the announcement vocabulary can be downloaded from the ARCs if necessary. Telephone Signalling Methods Analog--Analog signals are those that have continuously and smoothly varying amplitude or frequency. Speech signals are of this type when you consider tone, pitch and volume levels that vary according to the person speaking. When a person speaks into the transmitter on a telephone, the voice signals are made up of acoustical energy, which are then converted into electrical energy for transmission along a transmission medium. Analog carrier facilities may operate over different media, such as wire lines, multi-wire cable, coaxial cable, or fiber optic cable. Copper wire is the most commonly used for subscriber loops. A technique that allows for many signals to be sent along the same transmission path is called Multiplexing. Analog signals use Frequency Division Multiplexing or FDM. Digital--Instead of the voice signal being processed as an analog signal, it is converted into a digital signal and handled with digital circuits throughout the transmission process. When it arrives at the CO that serves the called telephone, it is converted back to analog to reproduce the original voice transmission. Pulse Code Modulation or PCM is when the binary signal is transmitted in serial form. Binary coding represents bits or binary digits at 0 and 1 levels. These levels have a definite time relationship with one another. Time Division Multiplexing or TDM is the type of multiplexing, sometimes abbreviated as MUX, done for digital transmission. Metallic--Metallic facilities carry only one Voice Frequency (VF) channel. Typically, a metallic facility is used to connect business or residential lines to a CO. Coaxial cable can be used to transmit both Analog and Digital signals as well as Metallic signals. VF channels have a 4000 Hz bandwidth, from 0 to 4000 Hz. However, the in-band range of the voice frequency is between 200 and 3400 Hz. Signals that are out of this frequency range but still within the VF channel are out of band signals. A supervisory equivalent to 2600 for out of band is 3700 Hz. The amount of VF channels vary according to the transmission facilities that are being used. CCIS (Common Channel Interoffice Signalling) is where control or supervisory signals are sent on a separate data link between switching offices. CCIS links operate at 4800 bps, or baud. Signal Transfer Points in the switch send the supervisory information over the dedicated link. This prevents supervisory tones from subscriber stations to register with the telephone network as a change in trunk status. Reverse Battery Signalling- When the called end answers, the polarity and condition of the Ring and Tip leads is reversed to indicate the status of the connection. Conditions for a call being placed, but not yet answered, is ground on the Tip and battery (the CO battery current is flowing through) on the Ring. When the called party answers, by the action of relays in the switching equipment, current is reversed in the calling subscriber loop and battery is placed on the Tip and ground on the Ring, which remains during the talking. E and M- Leads connecting switching equipment to trunk circuits are termed the E and M leads, for receive and transmit. The E lead reflects the far-end or terminating end condition of the trunk. Ground on the E lead indicates that a signal has been received from the other end. The E lead is open when the trunk is idle. The M lead reflects the the near end condition of the trunk. It is grounded when the trunk is idle, and goes to battery condition when the called party goes off hook. Long interoffice and short haul toll trunks use this signalling method. It should be noted that AC signalling is Alternating Current, and is used on the intertoll network, and interoffice and short haul toll trunks. DC, or direct current, is used on two wire or intraoffice connections, and local interoffice trunks. Single Frequency (SF)- Single Frequency is an in-band 2600 Hz signalling system. When a four wire trunk is idle, and is equipped for SF in band signalling, a 2600 Hz tone is being transmitted in both directions. When the trunk is seized at an originating position, the M lead is changed from ground to battery state. This removes the 2600 Hz supervisory tone from the outgoing trunk pair. The loss of the 2600 Hz will be detected at the far end by the SF signalling unit, changing the far end E lead condition from open to ground, causing switching equipment to function. When ground is restored to the M lead, replacing 2600 on the near end trunk, the pulsing of address information begins. Multi-Frequency (MF)- The MF pulsing method uses AC signals in the voice frequency range, and transmits address information between COs by combinations of only 2 of 5 frequencies. MF is used for the sending of address information, as mentioned before. Other signalling methods are still required for trunk control and supervision. There are six MFs comprising MF codes. These are 200 Hz apart in the 700-1700 range. Two frequencies are sent at once, thus explaining the term 'Multi frequency.' MF pulsing is initiated by manual keysets and the TSPS switchboard, or by MF outpulsing senders in ESS and Xbar. MF pulsing is very rapid and only occurs when a connection is being established. KPs, or Key Pulses, are used as a signal to start MF pulsing. STs, or STart tones are used as a signal to indicate the end of MF pulsing. As an example of MF signalling, take a toll switchboard trunk connected to a Xbar Central Office. The operator selects an idle trunk, and presses the KP button on the keyset to signal the distant sender or register link equipment to connect to a MF receiver. The S lamp on the keyset will light when the far end is ready to receive MF pulses. After keypulsing the digits of the called number, the operator presses the ST button, which indicates the end of pulsing and disconnects the keyset from the operator's cord circuit and extinguishes the KP and S lamps. At the terminating CO, the two MF tones of each digit are amplified and limited in the MF receiver unit associated with the incoming sender and register circuit. The frequencies are selected by channel filters in the MF receiver and then detected. The DC voltage that results will operate the proper channel relays to continue with the process of placing the call.