==Phrack Inc.== Volume 0x0b, Issue 0x3f, Phile #0x0d of 0x0f |=------------------=[ Holy Shit Another Phone Article ]=---------------=| |=------------------=[ Iz This the 80z or Smtg. ]=---------------=| |=----------------------------------------------------------------------=| |=---------------------------=[ d0nn13 n4rk0 ]=-------------------------=| 1 - Introduction 2 - Signaling 2.1 - What is Signaling? 2.1.1 - Signaling is Divided Into a Few Categories 2.1.2 - Other Things to Look Up 2.2 - 2600 HZ 2.3 - CCIS - History - Our lead into section 3. 3 - CCS7 (Common Channel Signaling 7) 3.1 - Understanding CCS7 3.2 - The Protocol 3.2.1 - MTP - Message Transfer Part 3.2.2 - TCAP - Transaction capabilities application part 3.3 - The Messages 3.4 - ISUP messages 3.5 - CCS7 Nodes 3.6 - Linkz 4 - DMS100 - CCS7 Command guide 4.1 - Introduction 4.2 - CCS7 Menu Descriptions 4.3 - Conclusion 5 - Appendix --[ 1. Introduction Before I begin let me apologize for the delay of this document. After talking extensively with stealth and following his example with the SSH-1 MITM attack I decided to delay release of this document until all whitehats were given notice that their phones were tapped. (Incidentally some of you fucks are pretty sick, and should seek professional help ASAP). Anyway this document is about signaling, and protocols that grew out of old Native-American Habits of making smoke pictures as a way of communicating back and forth with each other. The only real useful bits are at the end in the command reference section being that all the rest of the stuff in here you should be able to find yourself. Begin Rant -> This is something that is really pissing me off lately - actually, the lack of effort people seem to do looking for themselves. None of you seem to be interested in ANYTHING at all. All you do is learn what is required to maintain your precious status within your precious BULLSHIT circles and then sit around and pretend that the world is a ./ away from you. Well wake the fuck up. None of you can control shit, the actions you can take at best are mildly annoying to the people that control you. Instead of gaining power you have grasped the social acceptance you probably lack in your real lives. What happened to the pursuit of things that interested you? What happened to wanting to learn something about the way the world works? What happened to the pursuit of exploration, technology, the feeling of the underground, the hope of the FUTURE, the power over the evil fuckers who want to overcharge, underproduce, and hold back everything because of their own fear. <- End Rant. Anyway this document will give you an overview of signaling and SS7/CSS7 networks as implemented in telephone networks around the world. The first few sections are mainly an idea overview from 10,000 km, and are mainly just terms so you can understand what the rest of them do, and for you to rape them and pretend you know all about phones to all your IRC friends. On a side note, anyone in #pla, #phreak, #2600 kill yourself. Since you are 2 dumb/lazy to actually READ shit before you attempt to school people with it, kill yourselves. You are nothing more than wastes of space, and I really wouldn't have a problem with any of you just being that, but you try to infiltrate all that is pure and good in the underground and ruin it for your own lack of self esteem, intelligence, and capabilities. You are fucking over us, and fucking up the world. It's your fault that shit gets leaked, innocents get destroyed, and fear spreads because you do not comprehend your actions, nor the power of the information you beg for. But because last time, I got 50k emails asking me "whats' a switch?" (most of them were from 2600 readers) I decided to include a quick overview here. Remember this is from 10,000 kmz up and only really written to give you a basic idea in order for you to actually take the initiative and investigate further. --[ 2. Signaling ----[ 2.1. What is Signaling? I could be one of those guys who pastes crap from the dictionary just to make his paper longer, but hopefully you're not idiots (all proof notwithstanding) and you know what signaling outside the telecommunications world is. Anyway within telephone networks, primarily your standard PTSN networks etc. you need a way for equipment to notify other equipment that things are happening. Things like - yo someone needs to place a call or yo how the fuq do i route this call to shinjuku etc. <- I just read that again it sounds pretty stupid, but we had to make sure everyone in various IRC channels which like to Dr about this section, It is EXTREMELY simple. -> DO NOT BE IMPRESSED <- (see average 2600 dork) ------[ 2.1.1. Signaling is Divided Into a Few Categories (oh yeah before I go on I should note that I'm writing all this stuff from memory, so I might have got some stuff screwed up, but since you can look up everything on this section via Google, I don't think it matters all 2 much.) A. Supervisory These things were defined in order to monitor the status of lines/trunks. They let the switching system know if the line/trunk is busy/idle etc. One of the customer based functions of these things is to monitor loop current. So basically when you pick up your phone and the switch hook closes the path between Tip/Ring of the cable pair you get some juice blasted through to your ring lead. The current detection stuff supervises the line (see title) and notifies your line controller which then notifies the main switch which then notifies itself repeatedly 42 times. Thus the meaning of life is discovered. <- (Anyone truly into phones should recognize this joke, if you don't go read every txt file written since 1972 + the Hitchiker's Guide, and then shoot yourself.) B. Addressing These things are used to identify which telephone has been called; you of course should know what this means. But if you don't, think about how you identify to the system what phone number you're calling. Yeah! from those little buttons on your phone. DTMF, Dual Tone MultiFrequency tones are used to send signals to a dial register at your local phone office. Which can then be processed by the system (So far all this shit is looking pretty simple right?) C. Alerting Ok so far we have information on how signals are sent to alert the switch that your about to make a call and information on the type of signals sent to the switch to get it to know what number your calling, so what's next? (We'll get into routing paths/Trunks and crap like that later for now assume both numbers are within the same exchange) So next the switch has to Alert the remote party that its being called. Ringing Signals are sent to the remote parties telephone which cause it to... RING!@# When the call is picked up, current flowz into the loop. D. Progress Signals This is the only other thing that really needs to happen during telephone operation that you need to know about while your making a call. There are different stages of course to a call, dial-tone/Busy Tone/Ring back and recordings. These signal the progress of the call on the network to the person who is calling. ------[ 2.1.2. Other Things to Look Up Well, the above is a basic start, to explore a bit more about customer/telephone/interaction and how information gets to where it's supposed to go you can take a look at the following subjects. A. Loop Signaling B. DTMF C. Step by Step Switching (SXS) /Loop Signaling Implementations D. Loop Signaling/Crosstalk Problems E. Reverse Battery Signaling (see SXS) F. Ground Start Signaling G. Early Trunk Signaling Actually this is something we should take a look at. Since it will give you a very basic idea of how this crap used to work. These early systems were in-band/analog systems. The early circuits all used loop signaling (Look it Up). Gradually this progressed into callers connecting to Trunk Circuits with Loop Signaling but then the trunk circuit converting the signals into Transmit/Receive Signals (E&M)... anyway this can all be explored further outside the scope of this paper. It's only neat because I believe this is one of the key POI's which led to a lot of other shit to be developed. H. FDM/TDM carrier systems I. T1 J. SuperFrame K. Extended Super Frame ----[ 2.2 2600hz (or all the crap above has been explained so many times I really shouldn't have wrote it) Also known as - Inband vs Out of Band Signaling systems can be analog/digital and inband/out of band. EVERYONE should know exactly what this means but for those of you who don't: in the context of the telephone system In-band Signals are sent over the voice circuit (the one you talk on) (BEEP/KERCHUNK!) and out of band are sent over a different circuit. Your local telephone equipment uses analog, in-band signaling (changing) over the local loop. The old Trunk Circuits and the old long distance networks were all using the same thing until the 70's/80's (see the BlueBox linenoise thing in Phrack 62) They used both (SF) Singal frequency of (MF) <- FIGURE IT OUT. The 2600-hz tone meant the trunk was on-hook/idle. Dialing over these circuits was done by sending a set of tones down the line which signaled the calling number etc. These tones are a bit different then DTMF, and I couldn't find the chart to paste it here so you can look that up as well if your interested. Actually I'm tired of writing this part in general so just look up anything on blueboxing in general and you should get much more details. In essence because the circuits used In-Band Signaling and the tool trunks were using MF signals over the voice circuit, you could muck with it and do lots of interesting shit. Thus the movement (rather quickly) of everything to Out of Band Signaling. Extra Crap to Look up: ANI CCIS E&M signaling ----[ 2.3 CCIS - History - Our lead into section 3. All you need to know here is that the Out of band signaling network developed by I think AT&T was known as Common Channel Interoffice Signaling. Soon converted into a digital bit-stream as everything started to become "Modern" <- heh. The system could decode/receive/generated digital messages instead of having to look for electrical changes. There's a ton of stuff to go off and explore from here, as we get into modern stored program controlled switching systems, AIN (advanced Intelligent Network) systems, etc. Anyway CCIS basically evolved into what is now standardized and accepted all over the world. (Sting like a butterfly, float like a bee) CCIS #7 or Signaling System 7 --[ 3. CCS7 (Common Channel Signaling 7) ----[ 3.1. Understanding CCS7 (What the hell is it or what might have seemed unclear before) CCS7 is an out of band message signaling system. All SPC switching systems are generally connected via SS7. The capabilities the system offers are only limited by the features of the individual switches themselves. It's a bit difficult to think of SS7 as just a protocol, or messaging system, when in fact the definition describes the network that it runs on, as well as all the protocols encompassed etc. ----[ 3.2. The Protocol: The CCS7 protocol is the operating software of the CCS7 system. The protocol consists of layers. These layers correspond to the levels of activity required to support the interconnection and exchange of information between the users of a communications system. CCS7 Layers 4. Network application proc 3. Message Transfer Part : Network 2. Message Transfer Part: Link 1. Message Transfer Part: Physical ------[ 3.2.1. MTP - Message Transfer Part These layers form an interface that conforms to X.25. The MTP is a Datagram service. The address code is a 14bit signaling point address code. The Physical layer implements channelization and framing on the link. The Link Layer controls point-to-point connectivity, performs error detection and correction, synchronization, and flow control and assembles bits into signaling units. The Network Layer with signaling connection control part (SCCP), controls end-to-end connectivity, notifies A. Management Control: This updates routing and translations based on traffic congestion etc. and keeps track of application status and informs the user when apps aren't available B. Message Handler: This transfers signaling data units, Initiates Global title Translation, routes messages through the network and within the node, based on the subsystem number, and checks the status of the destination, and routes messages to MTP, ISUP or subsystem number ------[ 3.2.2. TCAP - Transaction capabilities application part This provides a set of generic procedures for applications based on transactions. It also Controls the non-circuit related information transfer between two or more nodes in a networks ------[ 3.2.3. ISUP: ISDN User Part For Isdn users, this provides all the signaling. The nodes on a CSS7 network are phone switches and signal relay equipment. They include: A. Signaling Point This is what supports the voice trunk capability . B. Service Switching Point (SSP) This node provides the functions and communications between databases, toll calls etc. C. Signaling Transfer Point (STP) This node transports and relays messages between CCS7 nodes D. INODE (integrated Node) A combination of all of the above. The Signaling Links are the signaling terminal equipment and transmission facilities which are in place whic facilitate communication between CCS7 nodes. See below for the types of Links. A-links Connect SPs, SSPs, and SCPs to STPs B-links Connect mated STPs in a SL quad C-links Connect two STP nodes to create an STP pair D-links Connect secondary STP pairs to primary STP pairs E-links Connect SPs, SSPs, and SCPs to remote STP pairs F-links Connect SPs, SSPs, and SCPs to each other ----[ 3.3. The Messages: In a CSS7 Network, The system sends signaling information with three types of signaling units: A. Link Status Signal units (LSSU) These report SL changes of state and are the unit's with the highest routing priority. B. Message Signal Units These things are what facilitates transfer of information between nodes C. Fill in Signal Units - These fill in the gaps between Transactional Capabilities Application Part (TCAP) enables deployment of advanced intelligent network (AIN) services by supporting information exchange between signaling points using SCCP. TCAP messages are contained within the SCCP portion of a Message Signal Unit (MSU). TCAP messages consist of a transaction portion and a component portion. (^^ Yay for Cisco.com and cut/paste) In essence what that well worded definition said was; A tcap message has 2 parts, transaction part and the component part. The Transaction part of the message associates the message with whatever application transaction is ongoing. The application process transaction is one or more messages exchanged between (GASP) application processes at different signaling points. The component part of the message makes sure that information, within the transaction is formatted and exchanged correctly. ----[ 3.4. ISUP messages - Watch now as I commit blatant copyright violation. ISUP signaling sets up, monitors, and takes down CCS7 calls on ISUP signaling trunks. ISUP allows the following enhanced trunk call processing capabilities: faster call setup shorter holding times for call attempts that are not successful ability to carry voice and data at the same time ----[ 3.5 CCS7 Nodes DMS-STPs are nodes that transfer messages between incoming and outgoing SLs. The DMS-STPs do not originate or terminate messages, except NWM information messages. DMS-STPs are deployed in pairs. If one DMS-STP fails, the mate takes over to make sure there is no interruption in service. [Brief Interlude] CCS7 has three major components, the service switching point (SSP), the signal transfer point (STP) and the service control point (SCP) Exchanges using CCS7 have an SSP, and issue requests for shit (trunk circuits) via SSP. the SSP links to an STP which is basically a router which connects SSP'z to SCP's. or SSP'z to SSP'z. SCP's are databases that hold circuit, routing and customer infoz [end Brief Interlude] A DMS SP/SSP is a switching office that supports CCS7 voice trunk capability (ISUP messaging). An SP provides an interface between subscriber lines and the CCS7 network. An SSP supports TCAP messaging, which allows the SSP to request information from CCS7 databases, like 800 Service. (Oh crap U should have described that Inode Thing before better or at least correctly) An INode is a combined SSP and STP and it supports all the functions of an SSP and an STP. The combination allows the use of a single site and a reduced number of frames and cabinets. By integrating CCS7 elements into a single node, operating companies can accrue cost savings that result from shared equipment, reduced transmission facilities, and integrated operations, administration, and maintenance. (Anyway lets end section 3 here. Since I did promise earlier to provide links to things you could use to find more information 3.6 is the linkz section) ----[ 3.6. Linkz http://www.google.com http://www.cisco.com http://www.yahoo.com http://www.dogpile.com http://www.lycos.com http://www.altavista.com Happy hunting! --[ 4. DMS100 - CCS7 Command guide (The useless shit you want to impress your friends with) ----[ 4.1. Introduction Ok so here is a nice little intro to some commands and how you can muck about with signaling. This is just the "Oh Neat" Part of this document in reality because none of this is useful unless you actually understand every part of every thing written above. Which is impossible since it hardly even makes sense in this document in the first place. The point of course is for you to think (oh neat) and then go research all the crap I wrote about above and memorize whatever information you want so you can explore your world. We're gonna describe a few Test tools for yah here. The CCS7 Test utility (C7TU), the CCS7 Bit error rate test (C7BERT) and some information on how to perform manual loopback tests. A. CCS7 Test Utility C7TU lets you monitor messages on CSS7 links using the C7TULINK command. In addition with some password guessing you can use C7TULINK_ILPT7 to build messages yourself and test the effect on random shit. Oh you can also intercept messages before they are sent out to the network. So lets start with the basic hierarchy. You'll note that my basic warning about fucking up the switch is missing. This is because I highly doubt any of you will ever in your lives get this far, and if you do, you'll probably know enough not to break things stupidly. >C7TU will give you access to >HELP C7TULINK Accesses message monitoring commands C7TUPRT Displays C7TU reports recorded on a device by C7TUREC C7TUREC Records C7TU reports from peripheral modules (PM) to a device DPC Queries the state of a routeset. Any state change produces a C7TU message. Also, enables and disables reports. HELP Displays information about C7TU commands MSGCODE Displays all message codes that can be used to specify the CCS7 messages to be monitored through the C7TULINK subdirectory QUIT Exits the C7TU directory >C7TULINK >HELP ALTER Modifies a test message * MASK Changes specified bytes in the Mask array in MASK table entries MATCH Changes specified bytes in the Match array in MATCH table entries MONITOR Monitors for specified CCS7 messages QUIT Quits from C7TULINK level back to C7TU level REMOVE Removes a monitor or intercept request from the MATCH table, a message from the message table, or a link that was previously selected with the SELECT command RESTORE Restores the message table to the LIU7 following a restart in the central controller SELECT Selects up to four LIU7s for monitoring and intercepting messages on associated links. SEND Takes a message from the message table and injects it into a link * STATUS Displays the status of the C7TULINK environment Everything Marked with a * is basically only useful if you have the right password; actually I don't think its even visible as an option if you don't. Ok so all that stuff sounds pretty cool but how do you actually use it, what the hell are those tables, and what's a LIU7? Ok well an LIU7 is a Link Interface Unit. The C7TU Match table is a table, which contains up to 8 entries that specify criteria for monitoring or intercepting CCS7 Messages. These commands require quite a bit of research to actually be able to use as each of them has a ton of parameters etc. I really do know with an Example: >MONITOR LINK LINKSET1 1 IN ANSI LABEL NATL 0 1 2 3 4 5 6 7 SLTM PARMS 01 10 > DUMP 0 MAP display C7TU MON SIO DPC OPC SLS TYPE NUM DIR NET NI PR SI MEM CLU NET MEM CLU NET 0 IN ANSI NATL 00 SNTS 003 002 001 006 005 004 07 SLTM 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Match: 00 04 00 00 82 03 02 01 06 05 04 07 11 10 01 00 Mask: 00 FF 00 00 FF FF FF FF FF FF FF 1F FF FF FF 00 B. C7BERT It's totally useless for you to know anything about this so were going to skip it. C. Manual loopback blah fuck it, we are just gonna skip this too. I don't feel like explaining the entire command hierarchy again. If your ever on one of these things MAPCI;MTC;CCS;CCS7;C7LKSET is where you wan >HELP >C7LKSET >HELP ^^ this probably wont even work but you get the general idea here. Uhm ok I have to explain this better. Basically You have a hierarchy of commands/menu's which you are going to be working with, er lets just start this in the next section since its all about Menu systems. 4.2 Menu Systems The commands used at a MAP position are associated with a MAP display that contains a numbered list (or menu) of commands and parameters available from the level or sublevel that you access. Commands that you also execute from the accessed level, but that do not form part of the MAP display, are known as hidden commands. When we say menu here, we are referring to the level you are at within the overall hierarchy You can access the directories themselves and use the LISTST and PRINT dir commands in order to see a list of commands and directories from your current level. For the purposes of this document we are only going to look at CCS and PM. Of course CCS7 is in CCS and CS7BERT is in CS7LKSET under CCS7. So it's position within the hierarchy is actually >MAPC;MTC;CCS;CCS7;CS7LKSET;CS7BERT. I hope that makes some of this stuff clearer. ----[ 4.2. CCS7 Menu Descriptions Exploration of most things in this document is rather vague and left up to the reader. That's because there is a retarded amount of information you can learn about each command. C7BERT Use to evaluate the performance of a CCS7 signaling link before putting it into service or during fault isolation activities. A C7BERT test repeatedly transmits a 2047-bit pseudo-random pattern and subsequently checks the pattern to verify that no bit errors have occurred. C7LKSET Use to query and change the status of the links in a selected linkset. C7MSUVER Use to build message signaling units (MSUs), subject them to the screening rules of the CCS7 link interface unit (LIU7), and display the results of screening rules that were encountered. C7OMAP Use to access the MRVT level. C7OMAP and MRVT levels are applicable only to signaling transfer point (STP). C7RTESET Use to display info housed in a link peripheral processor (LPP) with single F-bus configuration. HLIU Use to perform maintenance activities on the Common Channel Signaling 7 (CCS7) high-speed link interface unit (HLIU). This level is available only for STP nodes. HSLR Use to perform maintenance activities on the CCS7 high-speed link router (HSLR). This level is available only for STP nodes. LIM Use to perform maintenance functions on a link interface module (LIM). LIIS Use to access the F-bus maintenance system when the link interface module (LIM) is housed in an enhanced link peripheral processor (ELPP) with triple F-bus configuration. LIIU7 Use to perform maintenance activities on the Common Channel Signaling 7 (CCS7) link interface unit (LIU7). MRVT Use to init nodes. SCCPLOC Use to query or change the state of one or more signaling connection control part (SCCP) local subsystems. SCCPRPC Use to query or change the state of a SCCP remote point code. SCCPRSS Use to query or change the state of one or more SCCP remote subsystems. SEAS Use to query, test, and change the operating state of the Signaling, Engineering, and Administration System (SEAS). This level also has access to the permanent virtual circuits (PVC) level of maintenance. This level is applicable only to STP nodes. SVR7 Use to access the manual CCS7 server (SVR7) maintenance system. ----[ 4.3. Conclusion Each menu provides a ton of commands you can go over and mess with. The very basics I've given you above should give you a general start. I want to apologize at this point because in reality I did want to make this document a ton more in depth etc... but instead I must give you a quick glossary and give this to the editor before he shoots me for causing phrack to be delayed for so long. --[ 5. Appendix 800 Service An intertoll office service in which the called party subscribes to the service and pays for toll calls. Also known as inward wide area telephone service (INWATS). Advanced Intelligent Network (AIN) A set of software feature packages that enhances switch call processing capabilities to use centralized databases. These databases determine how AIN calls should proceed for further call processing. AIN also allows operating companies to design and deploy their own features and make these features available across private and public networks. A link A signaling data link that connects signal switching points (SSP) and service control points (SCP) to signaling transfer points (STP). billed number screening (BNS) A Common Channel Signaling 7 (CCS7) application process that performs a validation check on the number to which a call is billed. This check is initiated by the operator on operator-assisted and third-number billed calls. bit error rate test (BERT) A test that is used to measure the transmission quality of a loop. The BERT transmits a known bit pattern over a line and compares the reflected signal against the initial pattern. C7BERT Common Channel Signaling 7 (CCS7) bit error rate test. CCS7 link interface unit (LIU7) A peripheral module (PM) that processes messages entering and leaving a link peripheral processor (LPP) through an individual signaling data link. Each LIU7 consists of a set of cards and a paddle board provisioned in one of the link interface shelves of the LPP.enhanced network (ENET) module, provides hannelized access between the CCS7 network and ASUs. junctored network (JNET), network interface unit (NIU). common channel signaling (CCS) A signaling method in which information relating to a multiplicity of labeled messages is transmitted over a single channel using time-division multiplex (TDM) digital techniques. Common Channel Signaling 7 (CCS7) A digital message-based network signaling standard defined by the CCITT that separates call signaling information from voice channels so that interoffice signaling is exchanged over a separate signaling link. digital trunk equipment (DTE) frame A frame containing up to two dual-shelf digital trunk controllers (DTC). directory number (DN) The full complement of digits required to designate a subscriber's station within one numbering plan area (NPA)-usually a three-digit central office (CO) code followed by a four-digit station number. DMS SP/SSP DMS SuperNode Signaling Point/Service Switching Point (SPDMS SuperNode Signaling Transfer Point (DMS-STP). DMS SuperNode A central control complex (CCC) for the DMS-100 switch. The two major components of DMS SuperNode are the computing module (CM) and the message switch (MS). Both are compatible with the network module (NM), the I/O controller (IOC), and XMS-based peripheral modules (XPM). DMS SuperNode SE DMS SuperNode SE combines the core elements of DMS SuperNode architecture in a single cabinet. It provides the full range of DMS SuperNode features and services for small- and medium-sized standalone network applications. This feature compatibility extends the economic reach of DMS SuperNodenodes of a Common Channel Signaling 7 (CCS7) network. fill-in signal units (FISU) A type of signaling unit sent when the transmit buffer is empty. The FISU fills the gap between useful messages transmitted. frame supervisory panel (FSP) A device that accepts the frame battery feed and ground return from the power distribution center (PDC). The FSP distributes the battery feed, by means of subsidiary fuses and feeds, to the shelves of the frame or bay in which it is mounted. The FSP also contains alarm circuits. frame transport bus (F-bus) An 8-bit bus that provides data communications between a local message switch (LMS) and the link interface units (LIU) that are provisioned in a link peripheral processor (LPP). To ensure readability, two load-sharing F-buses are provided in an LPP. Each F-bus is dedicated to one of the two LMSs. frame transport bus (F-bus) tap A devicepart (SCCP) of the message transfer part (MTP). The SCCP global title translation (GTT) function is required to translate a GT into a valid network address. global title translation (GTT) The process that translates an application-specific address (such as a dialed 800 number) into the Common Channel Signaling 7 (CCS7) network address, usually that of the appropriate service control point (SCP). integrated services digital network (ISDN) A set of standards proposed by the CCITT to establish compatibility between the telephone network and various data terminals and devices. ISDN is a communications network that provides access to voice, data, and imaging services from a single type of connector. integrated services digital network user part (ISUP) A Common Channel Signaling 7 (CCS7) message-based signaling protocol that acts as a transport carrier for ISDN services. ISUP provides the functionality in a CCS7 network for voice and data services. junctored networkchannels per network pair (fully duplicated). Additional channels are established through the use of external junctors, internal junctors, and a digital network interconnecting (DNI) frame. Channels then can be routed directly, or use alternate routing, through the use of junctors, a DNI frame, and software control. link o In a DMS switch, a connection between any two nodes. O A four-wire group of conductors providing transmit and receive paths for the serial speech or message data between components of DMS-100 Family switches. Speech links connect peripheral modules (PM) to the network modules (NM). Message links connect NM controllers or I/O controllers (IOC) to the central message controller (CMC). linkset A collection of links connecting two adjacent signaling points in CCITT No. 6 Signaling (N6), Common Channel Interoffice Signaling No. 6 (CCIS6), and Common Channel Signaling 7 (CCS7). link status signal unit (LSSU) A type of signal unit that contains information about signaling unit state changes. The LSSU has priority over other types of signal units. local message switch (LMS) A high-capacity communications hub that controls messaging, equipped with test and service circuit cards and contains special buses to accommodate test cards for maintenance. The MTM provides an interface between the DMS-100 Family digital network and digital or analog test and service circuits. MAP Maintenance and administration position. A group of components that provides a user interface between operating company personnel and the DMS-100 Family switches. The interface consists of a video display unit (VDU) and keyboard, a voice communications module, test facilities, and special furniture. MAP command interpreter (MAPCI) A MAP level for accessing maintenance and other functional levels. message signal unit (MSU) A type of signal unit that contains signaling information. The MSUs are buffered until positive acknowledgement is received. message transfer part (MTP) A CCITT No. 7 Signaling (N7) protocol that provides a connectionless transport system for carrying Common Channel Interoffice Signaling No. 6 (CCIS6) and Common Channel Signaling 7 (CCS7) signaling messages between user locations or applications functions. Also known as message transport part. N7 signaling network A number of switching and processing nodes that are connected to each other by signaling links. CCITT No. 7 Signaling (N7) networks can contain the following nodes: signaling point (SP), signaling transfer point (STP), service control point (SCP), a network interface unit (NIU) A DMS SuperNode application specific unit (ASU) that provides channelized access for F-bus resident link interface units (LIU) using a channel bus (C-bus). The NIU resides in a link peripheral processor (LPP) frame. network module (NM) The basic building block of the DMS-100 Family switches. The NM accepts incoming calls and uses connection instructions from the central control complex (CCC) to connect the incoming calls to the appropriate outgoing channels. Network module controllers control the activities in the NM. network module controller (NMC) A group of circuit cards that communicates with the central message controller (CMC). The NMC is located in the network module (NM). The NMC organizes the flow of internal messages by directing messages to the peripheral modules (PM) or interpreting connection instructions to the crosspoint switches. node The terminating point of a link. A relative term: o in a switched communications network, the switching points, including patching and control facilities o in a data network, the location of a data station that interconnects data transmission lines o a unit of intelligence within a system; in a DMS switch, it includes the CPU, network module (NM), and peripheral modules (PM) per-trunk signaling (PTS) A conventional telephony method of signaling that multiplexes the control signal of a call with voice or data over the same trunk. remote switching center (RSC) A remote common peripheral module (CPM) that provides an interface with a large number of analog lines, digital trunking or both at a remote location. The RSC also handles remote-off-remote connections from other remote sites. routeset A logical group of Common Channel Signaling 7 (CCS7) signaling paths with the same destination point. routeset management (RSM) A service that transfers messages over the signaling network and helps to maintain the network by checking for link problems through the use of an integrity source. routing A telephony function that selects and connects a path from the originating terminal to a destination based upon application databases, and send a response message to the originator of the request. service switching point (SSP) A Common Channel Signaling 7 (CCS7) signaling node that interacts with the service control point (SCP) to implement special service code features. signaling connection control part (SCCP) A level of Common Channel Signaling 7 (CCS7) layered protocol. It supports advanced services such as E800 and service switching point (SSP) and the Automatic Calling Card Service (ACCS) feature. The main functions of the SCCP include the transfer of signaling units with or without the use of a logical signaling connection, and the provisioning of flexible global title translations (GTT) for different applications. signaling link (SL) The term used to describe the first two levels of the Common Channel Signaling 7 (CCS7) protocol: the physical level (level 1) and the link level (level 2). Level 2 fusignaling point/service switching point (SP/SSP) A Common Channel Signaling 7 (CCS7) node that combines the functions of a signaling point and a service switching point. Signaling System 7 (SS7) The American National Standards Institute (ANSI) version of the international CCITT Signaling System No. 7 that was developed for North American use. Signaling System #7 (SS#7) An international version of Signaling System 7 (SS7) based on the CCITT specification of SS7. signaling terminal (ST) The hardware that performs error checking, coding, and decoding of signaling messages. In Common Channel Interoffice Signaling No. 6 (CCIS6) and CCITT No. 6 Signaling (N6), it consists of a signaling terminal controller, a modem, and a modem interface card. In Common Channmessages. Signaling transfer points are deployed in pairs. If one STP fails, the mate takes over, ensuring that service continues without interruption. subsystem An application in a node that uses the routing functions of the signaling connection control part (SCCP). Subsystems are addressable entities. subsystem number (SSN) The identification of a subsystem located at a Common Channel Signaling 7 (CCS7) point code that can supply data. switch of activity (SWACT) In a DMS fault tolerant system, a switch that changes the states of two identical devices devoted to the same function. A SWACT makes an active device inactive and an inactive device active. Switch Performance Monitoring System (SPMS) A system that monitors all areas of switch operations and creates regular reports on performance. The reports are based on a wide range of index values computed from operational measurements (OM) generated by the switch. T1 The standard 24-hanCommon Channel Signaling 7 (CCS7) network. The protocol consists of message formatting, content rules, and exchange procedures. TCAP provides the ability for the service switching point (SSP) to communicate with a service control point (SCP). TCAP is used by the ISDN layer facility message to transport service information for transaction signaling, not associated with an active call, over primary rate interface (PRI) links. transmission link (TL) In a Common Channel Signaling 7 (CCS7) network, a T1 digital carrier terminating on a digital trunk controller (DTC). In the DMS switch, the TL is a single voice carrier on a DS30 link over conn functions in a service control point (SCP). Functions provided are: o local update validation o update distribution to query processors (QP) o database backup and restoration from disk or tape o coordination of local database audits |=[ EOF ]=---------------------------------------------------------------=|