WPCL 2BJ|x H   X  6p&6p&   H   c4 P  Fascicle VI.8 - Rec. Q.723 PAGE31  c4 P    HH  c4 P PAGE18  c4 P  Fascicle VI.8 - Rec. Q.723  HH HP X`h!(# X  X X  H c4 P 3.5   c4 P Backward set-up request message  H Hp P X`h!(# c4 P  The following type of backward set-up request message is specified and is identified by one of the heading codes H1. The other H1 codes in this message group are spare. HP X`h!(#X X  H3.5.1 General request messageCGeneral request message c4 P C Hp P X`h!(# The basic format of the general request message is shown in Figure 10/Q.723. K c4 P Figure 10/Q.723 CCITT 35570  c4 P   H Ё The following codes are used in the fields of the general request message:   a)pLabel: see S 2   b)pHeading code H0 is coded 0011   c)pHeading code H1 is coded 0001   d)pRequest type indicators  hpbit A: calling party category request indicator  hp0 no calling party category request  hp1 calling party category request  hpbit B: calling line identity request indicator  hp0 no calling line identity request  hp1 calling line identity request  hpbit C: original called address request  hp0 no original called address request  hp1 original called address request  H  hpbit D: malicious call identification indicator (national option)  hp0 no malicious call identification encountered  hp1 malicious call identification encountered  hpbit E: hold request indicator  hp0 hold not requested  hp1 hold requested  hpbit F: echo suppressor request indicator  hp0 no outgoing half echo suppressor requested  hp1 outgoing half echo suppressor requested  hpbit GH: spare  HH HP X`h!(#X X  H3.6   c4 P Successful backward set-up information messages  H Hp P X`h!(# c4 P  The following types of successful backward set-up information messages are specified and are each identified by a different heading code H1:  - address-complete message  - charging message.  HH HP X`h!(#X X  H3.6.1  c4 P Address-complete message  H Hp P X`h!(# c4 P  The basic format of the address-complete message is shown in Figure 11/Q.723. K c4 P Figure 11/Q.723 CCITT 35580  c4 P   The following codes are used in the fields of the address-complete message:   a)pLabel: see S 2   b)pHeading code H0 is coded 0100   c)pHeading code H1 is coded 0001   d)pMessage indicators Hp X`h!(# hpbits B A: type of address-complete signal indicators  hp0 0 address-complete signal  hp0 1 address-complete signal, charge  hp1 0 address-complete signal, no charge  hp1 1 address-complete signal, payphone  hpbit C:  subscriber-free indicator  hp0  no indication  hp1  subscriber-free  hpbit D:  incoming echo suppressor indicator  hp0  no incoming half echo suppressor included  hp1  incoming half echo suppressor included  hpbit E:  call forwarding indicator  hp0  call not forwarded  hp1  call forwarded  hpbit F:  signalling path indicator  hp0  any path  hp1  all signalling system No. 7 path  H  hph   pbits G H: spare, for national use (may be used to indicate call redirection, holding of the connection or the end-to-end signalling method to be used).  H Hp P X`h!(# Note - The address-complete signal without qualification is classified for the time being in the basic national category of signals. The use of this signal in the international network is for further study.  H3.6.2 Charging message (see Note)  The basic format of the charging message is shown in Figure 12/Q.723. K c4 P Figure 12/Q.723 CCITT 35585  c4 P   The following codes are used in the fields of the charging message:   a)pLabel: see S 2   b)pHeading code H0 is coded 0100   c)pHeading code H1 is coded 0010   d)pCharging information  H  (Possible formats and codes of the charging information field are shown in Annex A.)  Note - The charging message is classified, for the time being, in the basic national category of messages. The use of this message in the international network is for further study. HP X`h!(#X X  H3.7   c4 P Unsuccessful backward set-up information messages Hp P X`h!(# H c4 P 3.7.1 Simple unsuccessful backward set-up information message  H  The basic format of the simple unsuccessful backward set-up information message is shown in Figure13/Q.723. K c4 P Figure 13/Q.723 CCITT 35570  c4 P   The following codes are used in the fields of the simple unsuccessful backward set-up information message.   a)pLabel: see S 2   b)pHeading code H0 is coded 0101  c)pHeading code H1 contains signal codes as follows:  hp0000  spare  hp0001  switching-equipment-congestion signal  hp0010  circuit-group-congestion signal  hp0011  national-network-congestion signal  hp0100  address-incomplete signal  hp0101  call-failure signal  hp0110  subscriber-busy signal (electrical)  hp0111  unallocated-number signal  hp1000  line-out-of-service signal  hp1001  send-special-information-tone signal  hp1010  access barred signal  hp1011  digital path not provided signal  HX  hp1100  misdialled trunk prefix signal (for national use)  hp1101 G  hp to  U spare  hp1110 ,  HH  H3.7.2 Extended unsuccessful backward set-up information message  H  The basic format of the extended unsuccessful backward set-up information message is shown in Figure13a/Q.723. J c4 P Figure 13a/Q.723 CCITT 85960  c4 P   H Ё The following codes are used in the fields of the extended unsuccessful backward set-up information message:   a)pLabel: see S 2   b)pHeading code H0 is coded 0101   c)pHeading code H1 contains signal code 1111   d)pOctet indicator    c4 P H8(p P x҇  c4 P bi  ts  D C B A unsuccessful indicator  ˆH8(p P x҇ 0 0 0 0 spare  ˆH8(p P x҇ 0 0 0 1 subscriber busy  ˆH8(p P x҇ 0 0 1 0 G  ˆH8(p P x҇ to    U spare  ˆH8(p P x҇ 1 1 1 1 ,  ˆH8(p P x҇ G H F E: spare  ˆ HH  e) Signalling point code  Hh  hpThe point code of the signalling point in which the message is originated.  HH HP X`h!(#X X  H3.8   c4 P Call supervision message  H Hp P X`h!(# c4 P  The basic format of the call supervision message is shown in Figure 14/Q.723. K c4 P Figure 14/Q.723 CCITT 35570  c4 P   The following codes are used in the fields of the call supervision message:   a)pLabel: see S 2   b)pHeading code H0 is coded 0110   c)pHeading code H1 contains signal codes as follows:  hp0000  answer signal, unqualified  hp0001  answer signal, charge  hp0010  answer signal, no charge  hp0011  clear-back signal  hp0100  clear-forward signal  hp0101  re-answer signal  hp0110  forward-transfer signal  hp0111  calling party clear signal (national option)  hp1000 G  hpto  U spare  hp1111 ,  HH HP X`h!(#X X  H3.9   c4 P Circuit supervision message  H Hp P X`h!(# c4 P  The basic format of the circuit supervision message is shown in Figure 15/Q.723. K c4 P Figure 15/Q.723 CCITT 35570  c4 P с  The following codes are used in the fields of the circuit supervision message:   a)pLabel: see S 2   b)pHeading code H0 is coded 0111   c)pHeading code H1 contains signal codes as follows:  hp0000 spare  hp0001 release-guard signal  hp0010 blocking signal  hp0011 blocking-acknowledgement signal  hp0100 unblocking signal  hp0101 unblocking-acknowledgement signal  hp0110 continuity-check-request signal  hp0111 reset-circuit signal  hp1000 G  hpto  U spare  hp1111 ,  HH HP X`h!(#3.10   c4 P Circuit group supervision message  H Hp P X`h!(# c4 P  The basic format of the circuit group supervision message is shown in Figure 16/Q.723: K c4 P Figure 16/Q.723 CCITT 85970  c4 P   The following codes are used in the fields of the circuit group supervision message:   a)pLabel: see S 2  H  hpThe following interpretations apply to the CIC given in the label:  H  hpi) If the range field is not coded all zero the CIC given in the label is the first CIC within the circuit group or the first CIC within that part of the circuit group.  H  hpii) If the range field is coded all zero (national option) the CIC given in the label is a representative CIC within the circuit group.   b)pHeading code H0 is coded 1000   c)pHeading code H1 contains message codes as follows:  hp0000 spare  hp0001 Maintenance oriented group blocking message  Hh  hp0010 Maintenance oriented group blocking-acknowledging message  hp0011 Maintenance oriented group unblocking message  H  hp0100 Maintenance oriented group unblocking-acknowledgement message  hp0101 Hardware failure oriented group blocking message  H  hp0110 Hardware failure oriented group blocking-acknowledge message  hp0111 Hardware failure oriented group unblocking message  Hx  hp1000 Hardware failure oriented group unblocking-acknowledgement message  hp1001 Circuit group reset message  hp1010 Circuit group reset-acknowledgement message  Hx  hp1011 Software generated group blocking message (national option)  H  hp1100 Software generated group blocking-acknowledgement message (national option)  H  hp1101 Software generated group unblocking message (national option)  H  hp1110 Software generated group unblocking-acknowledgement message (national option)  hp1111 spare   d)pRange: in principle, two different codings are possible:  H  hpi) not all zero: The message is related to a whole circuit group or a part thereof, and includes a status field unless the message is the circuit group reset message. The number of consecutive circuits to be handled is indicated by the value contained in the range field increased by 1. The CIC of the first circuit to be handled is given in the label. The number of circuits to be indicated is 2 (range value 1) to 256 (range value 255).  Hx  hpii) all zero c4 P 1w HH 1) c4 P Range value zero is only for national use. w) c4 P  (national option): The message is related to a pre-determined circuit group. No status field is included. In this case the circuit group is addressed by means of a representative CIC within the circuit group.  H  Note - In national networks, the range field may not be used if only the concept of pre-determined circuit group applies.   e)pStatus field  H  All circuit group supervision messages except the circuit group reset message include a status field containing status indicator bits when the range field is not coded all zero. The number of status indicator bits is indicated by the value given in the range field increased by one.  H  The status field contains up to 256 one bit status indicators. The first status indicator bit is related to the circuit indicated by the CIC contained within the label, the second one is related to the circuit address by the CIC contained in the label increased by 1.  HH Ђ8D c4 P Figure 17/Q.723 CCITT 73570  c4 P   H Ё The CIC of the last circuit concerned is obtained by adding the value given in the range field to the CIC in the label. The status field consists of an integral number of octets. Bits within the last octet that are not used as status indicators are filled with zeros.  The status indicator bits are coded as follows:  - in all group blocking messages (MGB, HGB, SGB)  1pblocking  0pno blocking  Hx  -pin all group blocking-acknowledgement messages (MGB, HBA, SBA)  1pblocking acknowledgement  0pno blocking acknowledgement  - in all unblocking messages (MGU, HGU, SGU)  1punblocking  0pno unblocking  H  - in all group unblocking-acknowledgement messages (MUA, HUA, SUA)  1punblocking acknowledgement  0pno unblocking acknowledgement  - in the circuit group reset-acknowledgement message (GRA)  1pblocking for maintenance reasons  0pno blocking for maintenance reasons  HH HP X`h!(#3.11   c4 P Circuit network management messages  H Hp P X`h!(# c4 P  The following type of circuit network management message is specified and identified by one of the heading codes H1. Unallocated H1 codes in this message group are spare. HP X`h!(#X X  H3.11.1  c4 P Automatic congestion control information message  H Hp P X`h!(# c4 P  The basic format of the automatic congestion control (ACC) information message is shown in Figure18/Q.723: K c4 P Figure 18/Q.723 T110990088  c4 P   H Ё The following codes are used in the fields of the automatic congestion control information message.   a)pLabel: see S 2   b)pHeading code H0 is coded 1001   c)pHeading code H1 is coded 0001   d)pMessage indicators    c4 P H8( ҇  c4 P bi  ts  B A ACC information  ˆH8( ҇ 0 0 spare  ˆH8( ҇ 0 1 congestion level 1  ˆH8( ҇ 1 0 congestion level 2  ˆH8( ҇ 1 1 spare  ˆ HH Hp X`h!(# hpbitsHGFEDC%*spare Hp P X`h!(#Ђ8O c4 P ANNEX A 8F c4 P (to Recommendation Q.723) HP X`h!(#8J c4 P  Charging messages Hp P X`h!(#Ё c4 P  A.1h  Introduction  H  The application of Signalling System No. 7 in national networks was recognized from the beginning of the discussions about the signalling system. The result of this can be found throughout the specifications especially in those Recommendations dealing with the TUP. One of the points which is particularly of interest for an Administration is the possibility of transfer of charging information. Signalling System No. 7 allows for such a feature for charging a calling subscriber by defining a specific charging message as indicated in S 3.6.2. However, the detailed format, coding and related procedures are not given, mostly because this matter is very dependent on the circumstances within a specific national network. The following examples illustrate a particular implementation in a national network for telephony without exclusion of other possible solutions. A.2h  Starting points  H  Before describing in detail the messages involved, a number of starting points have to be adopted.  H   a)pThe first No. 7 exchange performs metering according to all possible tariffs.  H   b)pThe determination of a particular tariff is performed in a point somewhere in the network.  H   c)pThe receipt of messages containing charging information should be acknowledged within the call control procedures.  H   d)pAt dedicated moments the actual charging should be adapted.   e)pA variety of charging possibilities should be available.  HH  The effect of these starting points is:  H   a)pthe actual generation of charging units according to a particular tariff is always performed at the lowest level of the national public telephone network (local exchange);  H   b)pthe determination of tariffs for local and trunk calls is carried out in the local exchange and for international calls in the international exchange; however, also the use of a centre for determination of all kinds of tariffs is possible;  H   c)pthe transmission of charging information is assured at the highest level of the call control procedures and possibly inhibits call completion without receipt of charging information;  H   d)pcalls of long duration can be subject to different charging rates;  H   e)pthe application of charge free calls, specific charge on answer, time dependent charging during a call, additional (specific) charge during a call and a combination of these.  HH A.3h  Messages and procedures  H  To meet all the above mentioned requirements a number of messages are defined. HP X`h!(#X X  HA.3.1  c4 P Charging message Hp P X`h!(# c4 P  This message has to be sent for any call, charge free or not. In the procedure this is covered by the fact that the charging message has to be received during call set up before receipt of the address complete message.  If not, then the call should be cleared immediately.  H  The content of the message will vary depending on the actual tariff and this is indicated by a number of indicators indicating the presence of certain fields in the message.  Possible contents:   a)pcharge band  H  The indication of a certain charge band should allow the receiving exchange to charge a call according to a certain tariff including possible switchover times to higher or lower rates. This method results in a simple message but requires the receiving exchange to have all the information available related to all possible charge bands, national and international.  b)pexplicit charging indication  H  hpIn this case the message contains explicit indications of details of the tariff viz.  -hpnumber of charging units on answer (packet)  -hptime dependent tariff(s)  -hppossible switchover time.  H  This method results in a more complex message but does not require the permanent storage of any charging information.  HH HP X`h!(#X X  HA.3.2  c4 P Change message  Hx Hp P X`h!(# c4 P  A consequence of the adoption of the method with explicit charging indication (S A.3.1 b)) is the necessity to allow for tariff switchover for calls of very long duration or for calls which are answered just after the switchover time given in the message described in S A.3.1 b). The content of such at message is rather simple because it only contains the new applicable tariff and the actual switch-over time.  H  The procedure to acknowledge the receipt of the message cannot be found in the normal call control procedure, therefore an acknowledgement message (see S A.3.5) in the forward direction is used. If this acknowledgement message is not received within a certain time, the change message has to be repeated. HP X`h!(#X X  HA.3.3  c4 P Collection charging Hp P X`h!(# c4 P  For a variety of reasons it might be necessary to charge a subscriber during the call a certain amount. For this purpose a message is used indicating the number of charging units related to the amount for which the subscriber has to be charged.  The procedure to assure the receipt of this message is the same as described in S A.3.2 above. A possible further collection charging message should not be sent before receipt of the acknowledgement message and the charging confirmation message (see S A.3.4 charging confirmation). HP X`h!(#X X  HA.3.4  c4 P Charging confirmation  H Hp P X`h!(# c4 P  In relation with the message described in S A.3.3 a message in the forward direction is required indicating how many charging units actually are charged to the subscriber. This number should match to the number given in the collection charging message, otherwise it must be concluded that for some reason the order is not executed, e.g., a certain service should now be withheld to be furnished to the subscriber.  H  Again the procedure is the one as described in S A.3.2 above but in the opposite direction.  HA.3.5 Acknowledgement  H  To acknowledge the receipt of the messages described in SS A.3.2, A.3.3 and A.3.4, an acknowledgement message is used in both directions only indicating the receipt of the related message. A.4h  Formats and codes  HA.4.1 Charging messages  HA.4.1.1pCharge band P c4 P TABLEAU CCITT 86010  c4 P   -pCharge band  H  A charge indicates the combination of tariffs including switch-over times which is applicable for a certain period (e.g., day or week).  HH  HA.4.1.2pExplicit charging indication 8I c4 P tableau ccitt 86020  c4 P   - Message indicators  hpbit A:  tariff indicator current tariff (A)  H  hp0  packet charging field and tariff indicators current tariff (A) not present  H  hp1  packet charging field and tariff indicators current tariff (A) present  hpbit B:  tariff factor current tariff (A)  H  hp0  tariff factor field current tariff (A) not present  hp1  tariff factor field current tariff (A) present  hpbit C:  tariff indicator next tariff (B)  H  hp0  packet charging field and tariff indicators next tariff (B) not present  H  hp1  packet charging field and tariff indicators next tariff (B) present  hpbit D:  tariff factor next tariff (B)  hp0  tariff factor field next tariff (B) not present  hp1  tariff factor field next tariff (B) present  hph pbit H-E spare  - Packet charging field  hp0000  hp |P   number of charging units on answer  hp1111  - Tariff indicators  hp0000  tariff scale 0)/(no time dependent tariff)  hp0001  tariff scale I  H  hp |   X% |)/every scale indicates a certain step in seconds or parts thereof  hp1111  tariff scale XV  - Tariff factors  H  hpIf a call is charge free (A = B = C = D = 0) only the message indicator octet is present.  H  If a call is charge free from the start but may become chargeable (A = 1, B = 0, C = 1, D = 0/1), the packet charging field for the current tariff is 0000 and the tariff indicator for the current tariff indicates scale 0.  H  If a call is chargeable from the start but may become charge free (A = 1, B = 0/1, C = 1, D = 0) the packet charging field for the next tariff is 0000 and the tariff indicator for the next tariff indicates scale 0. If a call is chargeable according to only one tariff (A = 1, B = 0/1, C = 0, D = 0), also the time indicator is not present in the message. The actual tariff is determined by multiplication of the step indicated by the tariff indicator with the tariff factor which gives then a specific charging unit interval in seconds.  - Time indicator  hp000000 spare  hp000001 00.30 h  hp000010 01.00 h  hp |  |  hp |  |  hp110000 24.00 h  HH  HA.4.2 Tariff change message 8I c4 P Tableau ccitt 86030  c4 P    Message indicator  hpBit A:  tariff factor next tariff  hp0  tariff factor field next tariff not present  hp1  tariff factor field next tariff present  hpBits D-B: spare  Hx  - Tariff indicator, tariff factor and time indicator: see S A.4.1.2  HH HP X`h!(#X X  HA.4.3  c4 P Collection charging message Hp P X`h!(#Ђ8I c4 P tableau ccitt 86040  c4 P   H Ё The collection field contains the number of charging units which are to be charged to the calling subscriber. The field has a length of 8 bits so a maximum of 256 units is possible. HP X`h!(#X X  HA.4.4  c4 P Charging confirmation message Hp P X`h!(#ЂP c4 P tableau ccitt 86040  c4 P   - Heading code H1  hpH1 = 0101 confirmation of packet charging  hpH1 = 0110 confirmation of collection charging  - Charging unit field  H  hpNumber of charging units which actually are charged to the calling party  HH  HA.4.5 Acknowledgement message 8I c4 P tableau ccitt 86050  c4 P   - Heading code H1  Hx  hph   pH1 = 1000 acknowledgement receipt of tariff review, collection charging or charging confirmation message HP X`h!(#X X ‚ References  H Hp P X`h!(#Ё[1]h  CCITT Recommendation Characteristics of primary PCM multiplex equipment operating at 2048 kbit/s, Rec. G.732.  H [2]h  CCITT Recommendation Characteristics of 2048-kbit/s frame structure for use with digital exchanges, Vol.III, Rec. G.734.  H [3]h  CCITT Recommendation Second order PCM multiplex equipment operating at 8448 kbit/s, Rec. G.744.  H [4]h  CCITT Recommendation Characteristics of 8448-kbit/s frame structure for use with digital exchanges, Rec.G.746.  H [5]h  CCITT Recommendation Language digit or discriminating digits, Rec. Q.104. [6]h  CCITT Recommendation Signalling Connection Control Part, Recs. Q.711-Q.714.