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Basic ISDN Course Overview of Recommendations

Basic ISDN Course Overview of Recommendations. Outgoing Facsimile Calls in ISDN.

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Basic ISDN Course Overview of Recommendations

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  1. Basic ISDN CourseOverview of Recommendations

  2. Outgoing Facsimile Calls in ISDN A terminal which supports both G2/G3 and G4 facsimile function or a G4 facsimile terminal attempting a G4 facsimile call (either polling or sending) should use the bearer capability according to the capabilities of the network, which may be either “circuit-mode 64 kbit/s unrestricted 8 kHz structured” or “virtual call”, or both of them, and provide the HLC information element with high layer characteristics identification “facsimile Group 4”. A terminal adapter (TA) supporting a G2/G3 facsimile terminal should use the 3.1 kHz audio bearer capability and should provide the HLC information element with high layer characteristics identification “facsimile Group 2/3”.

  3. Unsuccessful Outgoing Facsimile Calls in ISDN The actions to be taken by the calling facsimile terminal following an unsuccessful call attempt where incompatibility has been indicated (e.g. cause “incompatible destination” for calls within the ISDN, or call rejection with a suitable cause indication in the case of interworking with a dedicated network) require further study. The optimum condition to achieve compatibility in a call re-attempt greatly depends on the cause indication provided to the calling facsimile terminal and its capability to divert to the requested characteristics for the call re-attempt (see note). For a certain type of facsimile terminal these actions may include: i) A G2/G3 facsimile terminal should release the call and take no further action. ii) A G4 facsimile terminal should release the call. iii) A terminal which supports both G2/G3 and G4 facsimile function should release the call.

  4. Ad ii) The G4 facsimile terminal may initiate a call re-attempt, if a mismatch of the bearer capability has been indicated and it can match the requested characteristics, e.g. in the case where the “virtual call” bearer capability has been requested by the calling facsimile terminal and interworking with switched 64 kbit/s non-ISDN network takes place. Otherwise, it cannot take further actions and is unable to communicate with the called facsimile terminal. Ad iii) If interworking ISDN to PSTN has been indicated, or cause “incompatible destination” for calls within the ISDN, when the call has been rejected, the terminal which supports both G2/G3 and G4 facsimile function may initiate a re-attempt in the G2/G3 mode. It should use the 3.1 kHz audio bearer capability and should provide the HLC information element with high layer characteristics identification “facsimile Group 2/3”. If interworking ISDN, to switched 64 kbit/s non-ISDN network, has been indicated when the call has been rejected, actions according to item ii) may be appropriate.

  5. Incoming Facsimile Calls in ISDN For incoming calls originated within ISDN, the facsimile terminal should function as described for terminals supporting teleservices. For incoming calls from non-ISDN networks not able to convey high layer compatibility information such as the public switched telephone network (PSTN) or switched 64 kbit/s network, the facsimile terminal will receive the appropriate information indicating an interworking situation (call progress information). It should rely on the call progress information element to accept calls which are offered without the explicit information specifying high layer protocols, if it matches other elements describing the incoming call. Otherwise it should release or ignore the call (user options). In this case the directory number should be the overriding determinant of whether the terminal responds (provided the bearer capability is appropriate). In this case the use of Multiple Subscriber Number (MSN) supplementary service could be advisable because it is the only means to avoid having facsimile terminal accept calls which are not appropriate to it, e.g. incoming call from non-ISDN networks such as telephone calls or data calls.

  6. A TA supporting a G2/G3 facsimile terminal should answer the call if the following criteria are fulfilled: • a) the called party number information element, if present, contains a number which matches the number assigned to the TA; and • b) the bearer capability information element indicates the information transfer capability “3.1 kHz audio”; • and for incoming call from PSTN: • c1) the progress indicator information element indicates the progress description “call is not end-to-end ISDN” (incoming call from PSTN); • d1) the high layer compatibility information element is not present; and • e1) the called party sub-address information element is not present; • or for incoming call from ISDN [instead of c1), d1), e1)]: • c2) the progress indicator information element is not present (incoming call from ISDN); • d2) the high layer compatibility information element indicates high layer characteristics identification “facsimile Group 2/3”; and • e2) the called party sub-address information element, if present, contains a number which matches the sub-address assigned to the terminal. Incoming G2/G3 Facsimile Calls in ISDN 1

  7. Incoming G2/G3 Facsimile Calls in ISDN 2 • A terminal which supports both G2/G3 and G4 facsimile function should answer the call in the G2/G3 mode (including modem and codec functions) if the following criteria are fulfilled (incoming call from PSTN): • a) the called party number information element, if present, contains a number which matches the number assigned to the terminal; • b) the bearer capability information element indicates the information transfer capability “3.1 kHz audio”; • c) the progress indicator information element indicates the progress description “call is not end-to-end ISDN”; • d) the high layer compatibility information element is not present; and • e) the called party sub-address information element is not present.

  8. A terminal which supports both G2/G3 and G4 facsimile function (or a G4 facsimile terminal) should answer the call in the G4 mode (neither modem nor codec functions) if the following criteria are fulfilled (incoming call from switched 64 kbit/s network (non-ISDN): • a) the called party number information element, if present, contains a number which matches the number assigned to the terminal; • b) the bearer capability information element indicates the information transfer capability “unrestricted digital information” and transfer mode “circuit mode”; • c) the progress indicator information element indicates the progress description “call is not end-to-end ISDN (see Note); • d) the high layer compatibility information element is not present; and • e) the called party sub-address information element is not present. • Note – It may not always be possible to determine whether source is ISDN or 64 kbit/s switched network. Incoming G2/G3 Facsimile Calls in ISDN 3

  9. Incoming G2/G3 Facsimile Calls in ISDN 4 • A terminal which supports both G2/G3 and G4 facsimile function (or a G4 facsimile terminal) should answer the call in the G4 mode (neither modem not codec functions) if the following criteria are fulfilled (incoming call from ISDN): • a) the called party number information element, if present, contains a number which matches the number assigned to the terminal; • b) the bearer capability information element indicates the information transfer capability “unrestricted digital information” and a transfer mode which is supported by the called facsimile terminal (“circuit mode” or “packet mode”); • c) the progress indicator information element is not present; • d) the high layer compatibility information element indicates high layer characteristics identification “facsimile Group 4”; and • e) the called party sub-address information element, if present, contains a number which matches the sub-address assigned to the terminal.

  10. Bearer Capabilities for G2/G3 Facsimile Tx

  11. LLC Capabilities for G2/G3 Facsimile Tx

  12. HLC Capabilities for G2/G3 Facsimile Tx

  13. Information Transfer Phase

  14. Frame Construction Flag Flag Address Field Address Field Layer2 Header Control Field Control Field Info Field Layer3 Header Layer4 Header Layer5 Header Layer6 Header MMR/JBIG Frame Check Sequence Frame Check Sequence Flag Flag

  15. OSI 7 Layer Outline Application Process A Application Process B AP DATA Application AH APDATA Application Presentation PH Data Unit Presentation Session SH Data Unit Session Transport TH Data Unit Transport Network NH Data Unit Network Data Link F A C Data Unit FCS F Data Link Physical Completed frame Physical Physical Transmission Media

  16. Start-up Protocol PSTART MMR CDCL CDS CSUI CSUI CSS CSUI CSUI CSUI CSUI TCR TDT TDT TDT TDT TDT SQ CR I I I I I I SABM I I I I I I I I UA I I I I I SF CC I I I TCA TDT TDT RSSP RSUI RDCLP

  17. Release protocol MMR PEND PSTART MMR PEND CSUI CSUI CDPB CSUI CSUI CSUI CDE CSUI CSUI CSUI CSUI CSUI CSUI CSUI CSE TDT TDT TDT TDT TDT TDT TDT TDT CQ I I I I I I I I I I I I I I I I I DISC I I I I UA CF I I I TDT TDT TDT RSUI RSUI RSEP RDPBP RDEP

  18. G4/G3 Protocol Comparison 6 PSTART PSTART MMR MMR PEND 5 CDCL CDS CSUI CSUI CSUI CSUI CSUI CSUI CDE CSS CSUI CSUI CSUI CSUI CSUI CSUI CSUI CSUI CSUI CSE 4 TDT TDT TDT TDT TDT TDT TDT TDT TDT TDT TDT 3 I I I I I I I I I I I G4 2 I I I I I I I I I I I 2 I I I I 3 I I I I 4 TDT TDT TDT TDT 5 RSSP RSUI RSUI RSEP RDCLP RDEP 6 Post-protocol Pre-protocol Image Disconnection G3 DCS TCF PIX EOP DCN DIS CFR MCF

  19. S A B M E C o n n c t i o n U A P r o t o c o l S E T U P S E T U P C A L L P R O C l o S A B M E c C o n n c t i o n o U A t P r o t o c o l o r C o n n c t i o n A L E R T P A L E R T A l e r t ( O p t i o n ) P r o t o c o l h C O N N c C O N N D C o n n c t i o n C O N N A C K P r o t o c o l C O N N A C K B c h P r o t o c o l D I S C D I S C D i s c o n n c t i o n R E L l D i s c o n n c t i o n R E L P r o t o c o l o R E L C O M P P r o t o c o l c o R E L C O M P t D I S C o r D i s c o n n c t i o n D I S C P U A P r o t o c o l D i s c o n n c t i o n h U A c P r o t o c o l D L a y e r 3 L a y e r 2 L a y e r 2 L a y e r 3 L a y e r 2 L a y e r 2 L a y e r 3 D-Channel Protocol T x R x I S D N

  20. B-Channel Protocol T x R x S A B M C o n n e c t i o n U A P r o t o c o l S Q ( S I ) S F ( S F ) o n n e c t i o n C C R ( C N ) P r o t o c o l C C ( C A ) T C R C o n n e c t i o n T C A P r o t o c o l C S S R S S P C D C L P r o t o c o l R D C L P C D S P - S T A R T P I X P r o t o c o l P - E N D C D E R D E P P r o t o c o l C S E R S E P C Q ( C I ) D i s c o n n e c t i o n C F ( C F ) P r o t o c o l D I S C D i s c o n n e c t i o n U A P r o t o c o l L a y e r 6 L a y e r 4 L a y e r 2 L a y e r 2 L a y e r 4 L a y e r 6 L a y e r 5 L a y e r 3 L a y e r 3 L a y e r 5

  21. Service Switch When the incoming signal is from a G3 FAX Transmitting Side ISDN SETUPiG4FAXj G3 FAX CALL-PROC DISC Reason Display Value #088 iTerminal Attribute Causes Incompatibilityj Notified reason display value #088 is converted to Error Code ##1088 inside this machine.

  22. ISDN G4/G3 Fallback Transmitting Side ISDN SETUPiUnrestricted digital, G4FAXj CALL-PROC DISC Reason Display Value #088 iError Code##1088j REL G3 FAX REL-COMP SETUPi3.1kHz Audio, G3FAXj CALL-PROC CONN CONN-ACK

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