1、 STD-ITU-T RECMN d-BL*L-ENGL 1988 98b2571 Ob30191 O70 M INTERNATIONAL TELECOMMUNICATION UNION ITU=T 4.81 .I TELECOMMUNICATION STAN DARD I ZATI ON SECTOR OF ITU GENERAL RECOMMENDATIONS ON TELEPHONE SWITCHING AND SIGNALLING FUNCTIONS AND INFORMATION FLOWS FOR SERVICES IN THE ISDN STAGE 2 DESCRIPTION F
2、OR NUMBER IDENTIFICATION SUPPLEMENTARY SERVICES - DIRECT DIALLING-IN ITU-T Recommendation Q.81 .I (Extract from the Blue Book) STD*ITU-T RECMN Q-BL*L-ENGL 1788 48b2571 Ob30172 TO7 NOTES 1 ITU-T Recommendation 4.81 was published in Fascicle VI.l of the Blue Book. This file is an extract from the Blue
3、 Book and contains only the part of the Recommendation still in force. While the presentation and layout of the text might be slightly different from the Blue Book version, the contents of the file are identical to the Blue Book version and copyright conditions remain unchanged (see below). 2 teleco
4、mmunication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1988, 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or
5、mechanical, including photocopying and microfilm, without permission in writing from the ITU. Recommendation Q.81.1 STAGE 2 DESCRIPTION FOR NUMBER IDENTIFICATION SUPPLEMENTARY SERVICES - DIRECT DIALLING-IN 1 Direct dialling in DI) 1.1 Definition direct dialling in (DDI) enables a user to call direct
6、ly another user on a ISPBX or other private system without attendant intervention. 1.2 Description 1.2.1 General description A part of the ISDN number, which is significant to the user, is passed to the user. This supplementary service is based on the use of the ISDN number and does not include sub-
7、addressing. Note I - A similar method to select a terminal on a passive bus is described in the Stage 1 description of the supplementary service MSN. Note 2 - The caller may or may not find the ISDN number in the public directory. Recommendation E. 164 provides the flexibility for Administrations to
8、 use national numbering plans of fixed or variable number lengths. This flexibility also applies to DDI numbers, i.e. even within a given PABX DDI numbers of different lengths may appear. The number of digits used by a PABX supporting the DDI feature is not necessarily known by their serving local e
9、xchange nor by any other entity of the public network. The DDI number (fixed or variable length) is sent en-bloc or by over-lap sending from the exchange to the PABX or other private system which finally and automatically establishes a connection to the destination without the assistance of an opera
10、tor. 1.2.2 Qualifications on the applicability to telecommunication services No restrictions. 1.3 Derivation of afunctional model (Step 1) 1.3.1 Functional model description Two functional models are used to show the different requirements of DDI. Functional model 1 represents the situation where DD
11、I is used to address a terminal on a single ISPBX connected to the public network. Functional model 2 describes the situation where DDI is used to address a terminal within a private network consisting of several PBXs. Although functional model lcan be seen as a special application of model 2 it is
12、preferred to describe the two models independently to show different situations more clearly. Fascicle VI.1 - Rec. Q.Sl.1 1 - MODEL 1 Public network Private network FIGURE 1-1/Q.81 Two liinctioail modela for DDI 1.3.2 Description of the functional entities FE1 : Call control agent of the calling use
13、r FE2: Call control entity of the calling user FE3: DDI Access control to the private network (located in the public network) FE4: DDI Service control for the called user and access control in the private network FE5: Call control agent of the called user FE6: DDI Access control in the private netwo
14、rk FE7: DDI Service control in the private network for the called user. 1.3.3 Relationship to basic service The call setup procedures in the public network are mainly the same as for the basic service. FEI and FE2 therefore have the same functionality as CCA and CC. rl and r2 correspond to r1 and r2
15、 in the basic service. FE3 includes specific functionality of DDI in the relationship r3. FE4, FE6 and FE7 are entities in a private network that are only specified here as far as they are influenced by r3. The same applies for r4 and r5. 2 Fascicle VI.l - Rec. Q.Sl.1 1.4 1 .4.1 Diagrams Information
16、 flow diagrams (Step 2) The diagrams for model 1 are shown in Figure 1-2/43 1. FE2 -i X I l I I I I I I -! SETUP Req. Ind. r rl FE3 r3 FE6 SETUP fDDI No.) Req. Ind. I - g I I 1 l I I I Note 1 I Note 4 PROGRESS I Ind. Req. 1 v - Note 5 -. REPORT Note6 X Note 7 7 - Note 7 (alerting) Ind. Req. , SETUP
17、I -Conf. Resp. X 1 PROC I 1 X Ind. Req. Note 3 I REPORT Note6 (alerting) Ind. Req. SETUP Conf. Resp. SETUP Reo. Ind. I I SETUP (DOI No.) -I=- Ind. Req. REPOR1 Note6 .*I SETUP It“-.lx Req. lnd. X Through Connection of the switch FIGURE 1-2/Q.81 En bloc rcadiog to ao LSDN termld on I PABX 1.4.1.1 Diag
18、rams for model 2 - FEI - x rl SETUP Req. Ind. 1_1 PROCEEDING Ind. Res. Note 3 Note 5 REPORT Nota 6 (alerting) Ind. Req. SETUP. Conf. Resp. or parts of it Rw. Ind. Note 1 I I I I I I I SETUP (DDI No. Note 5 PROGRESS REPORT Note 6 (alerting) Ind. Req. SETUP Req. Ind, I I I I 1 I l I I I REPORT Note 6
19、(alerting) I Ind. Req. SETUP Conf. Resp. I CONNECT ,x Req. Ind. FIGURE 1-3/Q.81 En bloc tendins to I prlvite network Fascicle VI.l - Rec. Q.81.1 3 Notes to Figures 1-2/Q. 81 and 1-3/Q. 81 Note I - Optional signalling information which may be used to acknowledge seizure and/or for B channel negotiati
20、on. Note 2 - Optional signalling information which may be used to indicate complete address information. Note 3 - If not already sent, this signalling information may be sent to the originating user to indicate complete address information. Note 4 - If the PABX recognizes the receipt of complete add
21、ress information, this signalling information may be sent. Note 5 - On receipt of complete address information, this signalling information may be generated by the sub-PABX. If already sent by the PABX, it will not be transferred to the originating user. Note 6 - Instead of ALTERTING, a CONNECT sign
22、alling information may be sent directly in case of an automatically responding terminal. Note 7 - Optional early switch through backward transmission path. 1.4.2 Definitions The definitions for ACK, ADDRESS INFO, PROCEEDING, REPORT and SETUP are the same as for the basic service. 1.4.2.1 Meaning of
23、PROGRESS PROGRESS can be sent from the entity serving the called user to indicate that sufficient ADDRESS INFO was received to address a user terminal or access line. it is an unconfirmed information fiow. 1.4.2.2 Information content of PROGRESS B-channel information in r3 if not yet included in a p
24、revious sent information element. 1.5 SDL diagrams offunctional entities (Step 3) SDL diagrams are provided for FE3 covering the aspects of both functional models and giving the relation between r2 and r3. FE1 and FE2 are, as said, already covered by the basic procedures so that all aspects of DDI,
25、that are relevant for the public network, are covered in these diagrams. In the SDL diagrams only those procedures are described that deviate from the basic procedures. 4 Fascicle vI.1 - Rec. Q.Sl.1 STD-ITU-T RECMN Q-BL-L-ENGL 1988 iBb259L Ob30197 579 SETUP circuit (B-channel) Note 1 Option Through
26、connection A, B, SETUP req. ind. SETUP n11m14J FIGURE 14Q.81 (Sheet 1 of 3) DDI hinetions in FE3 Fascicle VI.l - Rec. Q.Sl.1 5 Negotiate SETUP req. I SETUP resp. Conf. FR OGR ESS req. ind. I resp. conf. req. ind. FIGURE 14/Q.81 (Sheet 2 of 3) DDI hincioor lo FB3 6 Fascicle VI.1 - Rec. Q.Sl.1 Note 1
27、f- Through Connection r-7 Active STD-ITU-T RECMN Q*BL*L-ENGL 1988 qBb2.591 Ob30L99 3bL = Clearing of the call - Alerting 0 SETUP Reip. Conf. SETUP Rerp. Conf. OPTION Disconnect tone gener. if applicable Through connection i Active FIGURE 144.81 (Sheet 3 of 3) DOI baaions la FR3 Fascicle VI.l - Rec.
28、Q.Sl.1 7 STD-ITU-T RECMN Q*BL-L-ENGL 1788 gBb2571 Ob30200 903 = Notes to Figure 1-4/Q. 81 (sheets I to 3) Note I - Through connection is generally only done when the setup confirmation is received from the called user. This is described in option A. In specific national applications through connecti
29、on may already be done in an earlier point in time. This is covered in options BI or B2 and requires further considerations. Note 2 - Negotiation of a B channel is not necessarily an independent information flow. It can be combined with the first backward information flow that is required for call c
30、ontrol. This information flow can be PROGRESS, REPORT (alerting) or SETUP. 1.6 1.6.1 SpeciBc actions in FE3 1.6.1.1 Channel selection selection procedure is as follows: Functional entity actions (Step 4) Negotiation for the selection of a B-channel will be permitted between the network and the PABX.
31、 The a) in the SETUP Request, the network will indicate one of the following: 1) 2) 3) any channel is acceptable. In cases 1) and 2), if the indicated channel is acceptable and available, the PABX selects it for the call. In case 2), if the PABX cannot grant the indicated channel, it selects any oth
32、er available B-channel and identifies that channel in the first information sent in response to the SETUP Indication. In case 3), the PABX selects any available B-channel and identifies that channel in the first information sent in response to the SETUP Indication. If no channel identification infor
33、mation element is present in the first response, the B-channel indicated in the SETUP Request will be assumed. If the B-channel indicated in the first response is unacceptable to the network, it will clear the call. When a B-channel has been selected by the PABX that channel may be connected by the
34、PABX. In case i), if the indicated B-channel is not available, or in cases 2), 3), if no B-channel is available and the PABX cannot proceed with the offered call, the PABX clears the call. channel is indicated, no acceptable alternative; or channel is indicated, any alternative is acceptable; or b)
35、c) d) e) The preferred solution for B-channel selection is alternative 1): B-channel is selected by exchange B. 1.6.1.2 Through connection fraudulent use of the connection without charging. public network. The general time for through connection in FE3 is, when setup is confirmed by the called user.
36、 This prevents As a consequence of this procedure all tones and announcements during call setup have to be generated in the As an alternative some network providers may allow for an early through connection. 1.6.2 1.6.2.1 Through connection In case of an ISDN terminal or sub-PABX connected to the PA
37、BX, the through connection of the B-channel in the PABX is done with the sending of SETUP to the terminal/sub-PABX. In the sub-PABX the through connection is done with the sending of SETUP to the terminal. In the terminal the through connection is done at the receipt of CONNECT ACKNOWLEDGE from the
38、PABX/sub-PABX. Specific actions in FE6 and FE7 8 Fascicle VI.1 - Rec. Q.Sl.1 In case of an analogue terminal connected to the ISDN PABWsub-PABX the through connection of the B- channel in the terminal is done with the sending of CONNECT to the ISDN PABWsub-PABX. In the ISDN PABNsub- PABX the through
39、 connection is done at the receipt of SETUP Confirmation from the terminal. Note that this case is for further study. 1.7 Allocation offunctional entities to physical locations Functional entities Scenario Call to ISPBX The mapping between functional entities and their possible physical locations is given in the following matrix. FE1 FE2 TE LE TE Call to private network NT2 FE3 LE LE FE4 NT2 TE I - FE7 NT2 Fascicle VI.l - Rec. Q.Sl.1 - 9
