ISUP Message

SS7 ISUP Messages

The below command is for changing the cause code in Huawei GSMC, please modify it and do the test,

MOD MSFP: ID=P20, MODTYPE=P1, BIT=2, BITVAL=0;

MOD OFC: ON="xxxx", ISUPSENDMSK=1;

MOD IMSGMSK: AOT=ISUP, SM=1, MSG=12, MV=USED, MC=YES, MM=12;

ADD IFLDVAL: SM=1, FLD=27, MSG=12, ACT=ALT, OLDV=31, NEWV=16;

Rollback command:

MOD MSFP: ID=P20, MODTYPE=P1, BIT=2, BITVAL=1;

MOD OFC: ON="xxxx", ISUPSENDMSK=16;

MOD IMSGMSK: AOT=ISUP, SM=1, MSG=12, MV=USED, MC=NO, MM=12;

MOD IFLDVAL: SM=1, FLD=27, MSG=12, OLDV=31, ACT=NA, NEWV=31;

RMV IFLDVAL: SM=1, FLD=27, MSG=12, OLDV=31;

SS7 ISUP Messages and their parameters :

Please Note : F = Fixed, O = Optional, V = Variable Length

You can find detailed information about parameters here : ISUP Parameters

ACM (Address Complete Message)

An Address Complete Message (ACM) is sent in the "backward" direction to indicate that the remote end of a trunk circuit has been reserved. The originating switch responds to an ACM message by connecting the calling party's line to the trunk to complete the voice circuit from the calling party to the called party. The terminating switch sends a ringing tone to the calling party's line.

Parameter Type Length (octet)

Message type F 1

Backward Call Indicators F 2

Optional Backward Call Indicators O 3

Call Reference O 7

Cause Indicators O 4-?

User to User Indicators O 3

User to User Information O 3-131

Access Transport O 3-?

Generic Notification Indicator O 3

Transmission Medium Used O 3

Echo Control Information O 3

Access Delivery Information O 3

Redirection Number O 5-12

Parameter Compatibility Information O 4-?

Call Diversion Information O 3

Network Specific Facility O 4-?

Remote Operations O 3-?

Service Activation O 3-?

Redirection Number Restriction O 3

End of Optional Parameters O 1

ANM (Answer Message)

When the called party answers, the destination switch terminates power ringing of the called line, removes audible ringing tone from the calling line and sends an Answer Message (ANM) to the originating switch. The originating switch initiates billing after verifying that the calling party's line is connected to the reserved trunk.


Message type F 1

Backward Call Indicators O 4


Call Reference O 7



Connected Number O 4-12



Call History Information O 4


Generic Number O 4-12










Call Progress Message (CPG)

CPG is sent in either direction during the set-up or active phase of the call, indicating that an event, which is of significance, and should be relayed to the originating or terminating access, has occurred.


Message type F 1

Event Information F 1

Cause Indicators O 4-?



Call Reference O 7






Call Diversion Information O 3










Circuit Group Response Message (CQR)

Sent in response to a Circuit/CIC Group Query message to indicate the state of all circuits/CICs in a particular range.


Message type F 1

Range and Status V 2

Circuit State Indicator V 3-33

Circuit Group Reset Acknowledgement Message (GRA)

GRA is sent in response to a Circuit/CIC Group Reset message indicating that the requested group of circuits/CICs has been reset. The message also indicates the maintenance blocking state of each circuit/CIC.


Message type F 1

Range and Status V 3-34

Confusion Message (CFN)

CFN is sent in response to any message (other than a confusion message) if the node does not recognize the message or detects a part of the message as being unrecognized.


Message type F 1

Cause Indicators V 4-20


Connect Message (CON)

CON is sent in the backward direction indicating that all the address signals required for routeing the call to the called party have been received and that the call has been answered.


Message type F 1



Call Reference O 7






Call History Information O 3








Remote Operations O ?




Continuity Message (COT)

COT is sent in the forward direction indicating whether or not there is continuity on the preceding circuit(s) as well as of the selected circuit to the following exchange, including verification of the communication path across the exchange with the specified degree of reliability.


Message type F 1

Continiuty Indicators F 1

Facility Reject Message (FRJ)

FRJ is sent in response to a facility request message to indicate that the facility request has been rejected.


Message type F 1

Facility Indicators F 1

Cause Indicators V 4



Information Message (INF)

INF is sent to convey information in association with a call, which may have been requested in an information request message.


Message type F 1

Information Indicators F 2

Calling Party's Category O 3

Calling Party Number O 5-12

Call Reference O 7

Connection Request O 7-9




Information Request Message (INR)

INF is sent by a node to request information in association with a call.


Message type F 1

Information Request Indicators F 2

Call Reference O 7




IAM (Initial Address Message)

An Initial Address Message (IAM) is sent in the "forward" direction by each switch needed to complete the circuit between the calling party and called party until the circuit connects to the destination switch. An IAM contains the called party number in the mandatory variable part and may contain the calling party name and number in the optional part.


Message type F 1

Nature of Connection Indicators F 1

Forward Call Indicators F 2

Calling Party's Category F 1

Transmission Medium Requirement F 1

Called Party Number V 4-11

Transit Network Selection O 4-?

Call Reference O 7


Optional Forward Call Indicators O 3

Redirecting Number O 4-12

Redirection Information O 3-4

Closed User Group Interlock Code O 6

Connection Request O 7-9

Origional Called Number O 4-12



User Service Information O 4-13



Propagation Delay Counter O 4

User Service Information Prime O 4-13


Generic Digit O ?

Originating ISC Point Code O 4

User Service Information Prime O 7



Generic Notification O 3


Generic Reference O 5-?

MLPP Precedence O 8

Transmission Medium Requirement Prime O 3

Location Number O 5-12


REL (Release Message)

A Release Message (REL) is sent in either direction indicating that the circuit is being released due to the cause indicator specified. An REL is sent when either the calling or called party "hangs up" the call (cause = 16). An REL is also sent in the backward direction if the called party line is busy (cause = 17).


Message type F 1

Cause Indicators V 3-?

Redirection Information O 3-4








signalingPoint Code O 4

Automatic Congestion Level O 4



Release Complete Message

A Release Complete Message (RLC) is sent in the opposite direction of the REL to acknowledge the release of the remote end of a trunk circuit and end the billing cycle as appropriate.


Message type F 1

Cause Indicators O 5-6


Subsequent Address Message (SAM)

SAM is sent in the forward direction following an initial address message, to convey additional called party number information.


Message type F 1

Subsequent Number V 3-10


User to User Information Message (USR)

USR is used for the transport of user to user signaling independent of call control messages.


Message type F 1

User to User Information V 2-130



Forward Transfer Message (FOT)

A message sent in the forward direction on semi automatic calls when the outgoing international exchange operator wants the help of an operator at the incoming international exchange. The message will normally serve to bring an assistance operator into the call if the call is automatically set up at the exchange.


Message type F 1

Call Reference O 7


Resume (RES), Suspend (SUS) Messages

RES is sent in either direction indicating that the calling or called party, after having been suspended, is reconnected.

SUS is sent in either direction indicating that the calling or called party has been temporarily disconnected.


Message type F 1

Suspend, Resume Indicators F 1

Call Reference O 7


Blocking (BLO) , Blocking Acknowledgement (BLA), Continuity Check Request (CCR) , Loop Back Acknowledgement (LPA), Overload (OLM), Reset Circuit (RSC), Unblocking (UBL), Unblocking

Acknowledgement (UBA), Unequipped Circuit Identification Code (UCIC)

Blocking (BLO) message sent only for maintenance purposes to the exchange at the other end of a circuit, to cause an engaged condition of that circuit for subsequent calls outgoing from that exchange. When a circuit is used in the bothway mode of operation, an exchange receiving the blocking message must be capable of accepting incoming calls on the concerned circuit unless it has also sent a blocking message. Under certain conditions, a blocking message is also a proper response to a reset circuit message.

Blocking Acknowledgement (BLA) message sent in response to a blocking message indicating that the circuit has been blocked.

Continuity Check Request (CCR) message sent by an exchange for a circuit on which a continuity check is to be performed, to the exchange at the other end of the circuit, requesting continuity checking equipment to be attached.

Loop Back Acknowledgement (LPA) message sent in the backward direction in response to a continuity check request message indicating that a loop (or transceiver in the case of a 2-wire circuit) has been connected.

Overload (OLM) message sent in the backward direction, on non?priority calls in response to an IAM, to invoke temporary trunk blocking of the circuit concerned when the exchange generating the message is subject to load control.

Reset Circuit (RSC) message sent to release a circuit/CIC when, due to memory mutilation or other causes, it is unknown whether for example, a Release or a Release Complete message is appropriate. If, at the receiving end, the circuit/CIC is remotely blocked, reception of this message should cause that condition to be removed.

Unblocking (UBL) message sent to the exchange at the other end of a circuit to cancel, in that exchange, the engaged condition of the circuit caused by a previously sent blocking or circuit group blocking message.

Unblocking Acknowledgement (UBA) message sent in response to an unblocking message indicating that the circuit has been unblocked.

Unequipped Circuit Identification Code (UCIC) message sent from one node to another when it receives a message on a circuit/CIC that is not provisioned for use.


Message type F 1

Circuit Group Blocking (CGB), Circuit Group Blocking Ack. (CGBA), Circuit Group Unblocking (CGU), Circuit Group Unblocking Ack. (CGUA) Messages

Circuit Group Blocking (CGB) message sent to the node to permit the switching equipment or maintenance system to remove from (and return to) traffic a group of circuits/CICs. A node receiving a Circuit/CIC Group Blocking message must be able to accept incoming calls on the group of blocked circuits/CICs unless it has also sent a Circuit/CIC Group Blocking message.

Circuit Group Blocking Acknowledgement (CGBA) message sent in response to a Circuit/CIC Group Blocking message to indicate that the requested group of circuits/CICs has been blocked.

Circuit Group Unblocking (CGU) message sent to the node to cause cancellation in a group of circuits/CICs of a blocked condition invoked earlier by a Circuit/CIC Group Blocking message.

Circuit Group Unblocking Acknowledgement (CGUA) message sent in response to a Circuit/CIC Group Unblocking message to indicate that the requested group of circuits/CICs has been unblocked.


Message type F 1

Circuit group supervision message type indicators F 1

Range and Status V 3-34

Circuit Group Reset (GRS), Circuit Group Query (CQM) Messages

Circuit Group Reset (GRS) message sent to release an identified group of circuits/CICs when, due to memory mutilation or other causes, it is unknown whether for example, a release or release complete message is appropriate for each of the circuits/CICs in the group. If at the receiving end a circuit/CIC is remotely blocked, reception of this message should cause that condition to be removed.

Circuit Group Query (CQM) message sent on a routine or demand basis to request the far-end node to give the state of all circuits/CICs in a particular range.


Message type F 1

Range and Status V 2

Facility Accepted (FAA), Facility Request (FAR) Messages

Accepted (FAA) message sent in response to a facility request message indicating that the requested facility has been invoked.

Facility Request (FAR) message sent from a node to another node to request activation of a facility.


Message type F 1

Facility Indicators F 1

Call Reference O 7


Connection Request O 9



Pass-along (PAM) Message

Pass-along (PAM) message that may be sent in either direction to transfer information between two signalingpoints along the same signalingpath as that used to establish a physical connection between those two points.


Message type F 1

User Part Test (UPT), User Part Available (UPA) Messages

User Part Test (UPT) message sent in either direction to test the status of a user part marked as unavailable for a signaling point.

User Part Available (UPA) message sent in either direction as a response to a user part test message, to indicate that the user part is available.


Message type F 1



Facility (FAC) Message

Facility (FAC) message sent in either direction at any phase of the call to request an action at another node. The message is also used to carry the results, error or rejection of a previously requested action.


Message type F 1



Message Compatibility Information O 4



Network Resorce Management (NRM) Message

Network Resource Management (NRM) message sent in order to modify network resources associated with a certain call. The message is sent along an established path in any direction in any phase of the call.


Message type F 1



Message Compatibility Information O 4



Identification Request (IDR) Message

Identification Request (IDR) message sent in the backward direction to request action regarding the malicious call identification supplementary service.


Message type F 1

MCID Request Indicators O 3-?

Message Compatibility Information O 4-?



Identification Response (IRS) Message

Identification Response (IRS) message sent in response to the identification request message.


Message type F 1

MCID Response Indicators O 3-?

Message Compatibility Information O 4-?






Segmentation (SGM) Message

Segmentation (SGM) message sent in either direction to convey an additional segment of an overlength message.


Message type F 1


Message Compatibility Information O 4-5

Generic Digit O ?

Generic Notification O 3




ISUP Message Flow

This section provides an introduction to the core set of ISUP messages that are used to set up and release a call. The ISUP protocol defines a large set of procedures and messages, many of which are used for supplementary services and maintenance procedures. While the ITU Q.763 ISUP standard defines nearly fifty messages, a core set of five to six messages represent the majority of the ISUP traffic on most SS7 networks. The basic message flow that is presented here provides a foundation for the remainder of the chapter. Additional messages, message content, and the actions taken at an exchange during message processing build upon the foundation presented here.

A basic call can be divided into three distinct phases:

Setup

Conversation (or data exchange for voice-band data calls)

Release

ISUP is primarily involved in the set-up and release phases. Further ISUP signaling can take place if a supplementary service is invoked during the conversation phase.

In Figure 8-3, part A illustrates the ISUP message flow for a basic call. The call is considered basic because no supplementary services or protocol interworking are involved. The next section, "Call Setup," explains the figure's message timer values.

Figure 8-3. Simple ISUP Message Flow[View full size image]

http://www.ss7-training.net/sigtran-training/images/1587050404/graphics/08fig03_alt.gif

http://www.ss7-training.net/sigtran-training/ch08lev1sec3.html#ch08lev2sec2

http://www.ss7-training.net/sigtran-training/ch08lev1sec3.html#ch08fig03

Call Setup

A simple basic telephone service call can be established and released using only five ISUP messages. In Figure 8-3, part A shows a call between SSP A and SSP B. The Initial Address Message (IAM) is the first message sent, which indicates an attempt to set up a call for a particular circuit. The IAM contains information that is necessary to establish the call connection—such as the call type, called party number, and information about the bearer circuit. When SSP B receives the IAM, it responds with an Address Complete Message (ACM). The ACM indicates that the call to the selected destination can be completed. For example, if the destination is a subtending line, the line has been determined to be in service and not busy. The Continuity message (COT), shown in the figure, is an optional message that is used for continuity testing of the voice path before it is cut through to the end users. This chapter's "Continuity Test" section discusses the COT message.

Once the ACM has been sent, ringing is applied to the terminator and ring back is sent to the originator. When the terminating set goes off-hook, an Answer Message (ANM) is sent to the originator. The call is now active and in the talking state. For an ordinary call that does not involve special services, no additional ISUP messages are exchanged until one of the parties signals the end of the call by going on-hook.

Call Release

In Figure 8-3, the call originator at SSP A goes on-hook to end the call. SSP A sends a Release message (REL) to SSP B. The REL message signals the far end to release the bearer channel. SSP B responds with a Release Complete message (RLC) to acknowledge the REL message. The RLC indicates that the circuit has been released.

If the terminating party goes on-hook first, the call might be suspended instead of being released. Suspending a call maintains the bearer connection for a period of time, even though the terminator has disconnected. The terminator can go off-hook to resume the call,




providing that he does so before the expiration of the disconnect timer or a disconnect by the originating party. This chapter discusses suspending and resuming a connection in more detail in the section titled "Circuit Suspend and Resume."

NOTE

Several different terms are used to identify the two parties who are involved in a telephone conversation. For example, the originating party is also known as the calling party, or the "A" party. The terminating party, or "B" party, are also synonymous with the called party.

Unsuccessful Call Attempt

In Figure 8-3, part B shows an unsuccessful call attempt between SSP A and SSP B. After receiving the IAM, SSP B checks the status of the destination line and discovers that it is busy. Instead of an ACM, a REL message with a cause value of User Busy is sent to SSP A, indicating that the call cannot be set up. While this example shows a User Busy condition, there are many reasons that a call set-up attempt might be unsuccessful. For example, call screening at the terminating exchange might reject the call and therefore prevent it from being set up. Such a rejection would result in a REL with a cause code of Call Rejected.

NOTE

Call screening compares the called or calling party number against a defined list of numbers to determine whether a call can be set up to its destination.



SS7 ISUP Message Format, Messages, Parameters and Timers

SS7 ISUP Message Format :

ISDN User Part Messages are carried on the signaling link by means of signal units. The service indicator for ISUP signaling is coded 0101.

The signaling information field of each signaling system 7 ISUP message consists of the following parts.

a) Routing label :For each individual circuit connection, the same routing label must be used for each message that is transmistted for that connection.

b) CIC - Circuit Identification Code :Network use CIC to identify which call circuit refers which signal.

c)Message Type Code :Consists of one octet field and it's mandatory for all messages. It uniquely defines the function and format of each ISUP message. Such as IAM, ACM, ANM etc.

d) The mandatory fixed part :These are fixed length mandatory parameters that every message should have. The position, length and order of parameters is uniquely defined by the message type. For this reason, the names of the parameters and the length of the indicators are not included in the message.

e) The mandatory variable part :Variable length mandatory parameters will be included in the mandatory variable part. Pointers are used to indicate the beginning of each parameter. Each pointer is encoded as a single octet. The name of the parameter and the order in which the parameters are sent is implicit in the message type. The parameters names are not included in the message. A pointer is also included to indicate the beginning of the optional part. Each parameter contains the parameter length indicator followed by the contents of the parameter.

f) The optional partThe optional part consists of parameters that may or may not occur in particular message type. Both fixed and variable length parameters may be included. Optional parameters can be transmitted in any order. Each optional parameter will include a parameter name (one octet) and the length indicator (one octet) followed by the parameter contents. After all parameters have been sent, an "end of optional parameters" octet which contains all zeros will be transmitted.

SS7 ISUP Messages, Parameters and Timers:

View all messages in detail, including the parameters

Isup Messages

ISUP MessagesBinary Values

Hex Values

Address complete 00000110 06

Answer 00001001 09

Blocking 00010011 13

Blocking acknowledgement 00010101 15

Call progress 00101100 2C

Circuit group blocking 00011000 18

Circuit group blocking acknowledgement 00011010 1A

Circuit group query 00101010 2A

Circuit group query response 00101011 2B

Circuit group reset 00010111 17

Circuit group reset acknowledgement 00101001 29

Circuit group unblocking 00011001 19

Circuit group unblocking 00011011 1B

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acknowledgement

Charge information 00110001 31

Confusion 00101111 2F

Connect 00000111 07

Continuity 00000101 05

Continuity check request 00010001 11

Facility 00110011 33

Facility accepted 00100000 20

Facility reject 00100001 21

Facility request 00011111 1F

Forward transfer 00001000 08

Identification request 00110110 36

Identification response 00110111 37

Information 00000100 04

Information request 00000011 03

Initial address 00000001 01

Loop back acknowledgement 00100100 24

Network resource management 00110010 32

Overload 00110000 30

Pass-along 00101000 28

Release 00001100 0C

Release complete 00010000 10

Reset circuit 00010010 12

Resume 00001110 0E

Segmentation 00111000 38

Subsequent address 00000010 02

Suspend 00001101 0D

Unblocking 00010100 14

Unblocking acknowledgement 00010110 16

Unequipped CIC 00101110 2E

User Part available 00110101 35

User Part test 00110100 34

User-to-User information 00101101 2D

View all parameters in detail

Isup Parameters

ISUP ParametersBinary Values

Hex Values

Access delivery information 00101110 2E

Access transport 00000011 03

Automatic congestion level 00100111 27

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Backward call indicators 00010001 11

Call diversion information 00110110 36

Call history information 00101101 2D

Call reference 00000001 01

Called party number 00000100 04

Calling party number 00001010 0A

Calling party's category 00001001 09

Circuit state indicator 00100110 26

Cause indicators 00010010 12

Circuit group supervision message type indicator

00010101 15

Closed user group interlock code 00011010 1A

Connected number 00100001 21

Connection request 00001101 0D

Continuity indicators 00010000 10

Echo control information 00110111 37

End of optional parameters 00000000 00

Event information 00100100 24

Facility indicator 00011000 18

Forward call indicators 00000111 07

Free phone indicators 01000001 41

Generic digits 11000001 C1

Generic notification 00101100 2C

Generic number 11000000 C0

Generic reference 01000010 42

Hop counter 00111101 3D

Information indicators 00001111 0F

Information request indicators 00001110 0E

Location number 00111111 3F

MCID request indicator 00111011 3B

MCID response indicator 00111100 3C

Message compatibility information 00111000 38

MLPP precedence 00111000 38

Nature of connection indicators 00000110 06

Network specific facilities 00101111 2F

Optional backward call indicators 00101001 29

Optional forward call indicators 00001000 08

Original called number 00101000 28

Origination ISC point code 00101011 2B

Parameter compatibility information 00111001 39

Propagation delay counter 00110001 31

Range and status 00010110 16

Redirecting number 00001011 0B

Redirection information 00010011 13

Redirection number 00001100 0C

Redirection number restriction 01000000 40

Remote operations 00110010 32

Service activation 00110011 33

Signaling point code 00011110 1E

Subsequent number 00000101 05

Suspend/resume indicators 00100010 22

Transit network selection 00100011 23

Transmission medium requirement 00000010 02

Transmission medium requirement prime 00111110 3E

Transmission medium used 00110101 35

User service information 00011101 1D

User service information prime 00110000 30

User teleservice information 00110100 34

User-to-User indicators 00101010 2A

User-to-User information 00100000 20

Isup Timers

Symbol

Default Value

Acceptable Range

Signal/Event

T1 15 sec. 15-60 sec. Release/Release Complete

T2 3 min. 3 min. Suspend/Resume

T5 5 min. 5-15 min. Release/Release Complete

T6 1 min. 1-2 min. On-hook, Reanswer

T7 20 sec. 20-30 sec.Initial Address, Address Complete, Subsequent Address,

Connect

T8 10 sec. 10-15 sec.

T9 3 min. 1.5 - 3 min. Address Complete, Answer

T10 4 sec. 4-6 sec. Last Digit Timer

T11 20 sec. 15-20 sec. Initial Address, Address Complete, Subsequent Address

T12 15 sec. 15-60 sec. User Part Available, UA

T13 5 min. 5-15 min. Blocking, Blocking Ack.

T14 15 sec. 15-60 sec. Unblocking, Unblocking Ack.

T15 5 min. 5-15 min. Unblocking, Unblocking Ack.

T16 15 sec. 15-60 sec. Reset Circuit, Release Complete

T17 5 min. 5-15 min. Reset Circuit, Release Complete

T18 15 sec. 15-60 sec. Circuit Group Blocking, Circuit Group Blocking Ack.

T19 5 min. 5-15 min. Circuit Group Blocking, Circuit Group Blocking Ack.

T20 15 sec. 15-60 sec.

T21 5 min. 5-15 min. Circuit Group Unblocking, Circuit Group Unblocking Ack.

T22 15 sec. 15-60 sec.

T23 5 min. 5-15 min.

T24 1.9 sec. 2 sec.

T25 5 sec. 1-10 sec.

T26 2 min. 1-3 min.

T27 4 min. 4 min.

T28 10 sec. 10 sec. SQM, SQR

T29 300 ms. 300-600 ms.

T30 5 sec. 5-10 sec.

T33 12 sec. 12-15 sec.

T34 2 sec. 2-4 sec.

T35 15 sec. 15-20 sec. Digit Collection

T36 10 sec. 10-15 sec.

T38 3 min. 2-3 min. On-hook, Reanswer

T39 12 sec. 12-15 sec. Information Request, Information

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ISUP Message

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Transcript of ISUP Message