1、 STD-ITU-T RECMN V-25 BIS-ENGL 17b m 48b257L Ub272Ub 864 INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU SERIES V: DATA COMMUN TELEPHONE NETWORK Interfaces and voiceband mc V.25 bis (1 O96) CATION OVER THE jems Synchronous and asynchronous automatic dialli
2、ng procedures on switched networks ITU-T Recommendation V.25 bis (Previously CCIT Recommendation) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services STD-ITU-T RECMN V.25 BIS-ENGL Lb H 48b259L b272117 7T m ITU-T V-SERIES RECOMMENDATIONS DA
3、TA COMMUNICATION OVER THE TELEPHONE NETWORK 1 -General 3 - Wideband modems 4 - Error control 5 - Transmission quality and maintenance 6 - Interworking with other networks For further details, please refer to ITU-T List of Recommendations. COPYRIGHT International Telecommunications Union/ITU Telecomm
4、unicationsLicensed by Information Handling Services- - STD-ITU-T RECMN V.25 BIS-ENGL 199b = 48b259L Ob27208 b37 FOREWORD The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The IT-T is responsible for studying technical, opera
5、ting and tariff questions and issuing Recommen- dations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the IT-T Study Groups which, in their
6、 turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). IT-T Recommendation V.25 bis was revised by ITU-T Study Group 14 (1993-1996) and was approved by th
7、e WTSC (Geneva, October 9-18, 1996). NOTE l. telecommunication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a 2. follows: The status of annexes and appendices attached to the Senes V Recommendations
8、 should be interpreted as - an annex to a Recommendation forms an integral part of the Recommendation; - an appendix to a Recommendation does not form part of the Recommendation and only provides some complementary explanation or information specific to that Recommendation. O ITU 1997 All rights res
9、erved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the IT. Recommendation V.25 bis (10/96) i COPYRIGHT International Telecommunications Union/ITU Telecommunic
10、ationsLicensed by Information Handling ServicesSTD-ITU-T RECMN V-25 BIS-ENGL L97b = 48b259L 0b27209 573 CONTENTS Scope Abbreviations and definitions General . Addressed call andor answer authorized by the DTE (circuit 108/2) . 4.1 interface procedure . Interface procedures at the calling data statio
11、n . Interface procedures at the answering data station . Direct call andor answer controlled by the DTE (circuit 10811) . 5.1 Interchange circuits involved interface procedure at the calling data station Interface procedure at the answering data station . 4.2 4.3 5.2 5.3 Line procedures 6.1 Line pro
12、cedure at the calling DCE . 6.2 Line procedure at the answering DCE Manual calling and answering Use of V.25 ter commands and indications . AnnexA . Test facilities . A.1 DCE self-test stage . DCE test with maintenance centre AnnexB - SDL Description ofthe addressed call - 10812 Response Mode . Appe
13、ndix I - General description of the V.25 bis commandindication syntax A.2 11 Recommendation V.25 bis (10/96) Page 1 2 2 3 3 15 15 16 16 17 18 19 19 20 20 20 21 21 21 22 24 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services STD*ITU-T RECMN
14、 V.25 BIS-ENGL L77b qBb257L Ob272LO 295 Recommendation V.25 bis SYNCHRONOUS AND ASYNCHRONOUS AUTOMATIC DIALLING PROCEDURES ON SWITCHED NETWORKS (revised in 1996) 1 Scope 1.1 This Recommendation specifies procedures for setting up data connections employing synchronous and asynchronous applications o
15、n switched networks. Users may wish to note that for asynchronous applications, an alternative procedure is specified in Recommendation V.25 ter which includes additional functionality for controlling and configuring DCEs. Means are provided in this Recommendation for the encapsulation of commands,
16、indications and messages specified for the V.25 ter protocol. 1.2 This Recommendation describes the sequence of events involved in establishing a connection between an automatic calling data station) and an automatic answering data station for DCEs specified for operation on switched networks. The s
17、ystem configuration is shown in Figure 1. Automatic calling data station Automatic answering data station I O0 - Series V.24 interface FIGURE 1N.25 bis Tl403080-971dD1 1 O0 - Series V.24 interface 1.3 The procedures are intended to be suitable for the following three types of call: a) b) c) serial a
18、utomatic calling data station to automatic answering data station; manual calling data station to automatic answering data station; serial automatic calling data station to manual answering data station. it is intended that data terminai equipment designed to control automatic calling equipment in a
19、ccordance with this Recommendation will also be suitable for use with manually controlled data circuit-terminating equipment, and also that data circuit-terminating equipment incorporating serial automatic calling equipment may be manually controlled where necessary. 1.4 The procedures described her
20、ein allow automatic calling equipment conforming to this Recommendation to interwork with automatic answering equipment conforming to Recommendation V.25. In this Recommendation, the term “data station“ is synonymous with the term “terminal installation for data transmission“. Recommendation V.25 bi
21、s (10/96) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services1.5 The data terminal equipment is responsible: a) during call establishment: i) for ensuring that the data circuit-terminating equipment is available for operation; ii) for pr
22、oviding the telephone number or selecting a telephone number pre-programmed into the data circuit-terminating equipment; iii) for deciding to abandon the call if it is unsuccessfully completed; b) after call establishment: i) for controlling data transfer; ii) for initiating disconnect at calling or
23、 answering data stations. 1.6 This Recommendation deals with call establishment and clearing. Any specific use of Recommendation V.24 interchange circuits herein described only applies during these phases. The management of interchange circuits and the line during the data transmission phase is not
24、part of this Recommendation. Details of interface procedures following the OFF to ON transition of circuit 107 on entry of the data transmission phase can be found in the relevant modem Recommendations. 1.7 Annex A gives guidance on the maintenance facilities which may be associated with an automati
25、c calling data circuit-terminating equipment. Methods for testing the automatic calling functions of the data circut-terminating equipment are included. 2 Abbreviations and definitions The following abbreviations are used in this Recommendation: DCE Data Circuit-terminating Equipment DTE Data Termin
26、al Equipment The following definitions apply to this Recommendation: 2.1 2.2 procedure. Recommendation X.210. command: An instruction issued by the DTE to the DCE as part of the automatic calling procedure. indication: An instruction or response issued by the DCE to the DTE as part of the automatic
27、calling NOTE-In this Recommendation the terms “indication” and “response” are not to be taken in the sense defined in 2.3 parameter: A variable which may accompany Commands or Indications. 2.4 DCE associated with it to perform the call establishment function. automatic calling: A procedure by which
28、a DTE, by use of certain V.24 interchange circuits, instructs the 3 General An automatic calling and/or answering data station in accordance with this Recommendation can be operated in two modes: The “addressed call and/or answer authorized by the DTE (circuit 108/2)” mode gives a calling data stati
29、on extensive facilities by means of instructions and indications exchanged between the DTE and the DCE on circuits 103 and 104. It gives an answering data station the capacity to accept a prior? an incoming call. The “direct call and/or answer controlled by the DTE (circuit 108/l)” mode gives a call
30、ing data station the capacity of calling a number (or a sequence of numbers) pre-recorded in the DCE, by means of the 108/1 control circuit. It gives an answering data station the capacity of accepting incoming calls on a “per call” basis. NOTE-Although automatic answering data stations as well as a
31、utomatic calling and answering data stations may - - implement both modes of operation, they should be configured to operate in a specific one of the two modes. 2 Recommendation V.25 bis (10/96) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling S
32、ervices STD-ITU-T RECMN V.25 BIS-ENGL 179b 9Ab2571 Ob27212 ObA W 4 Addressed call and/or answer authorized by the DTE (circuit 108/2) 4.1 Interface procedure 4.1.1 Interchange circuits involved The interchange circuits used in this automatic calling/answering procedure are listed in Table 1. Their u
33、se during the automatic calling/answering procedures is described below. TABLE 1N.25 bis 103 104 106 107 10812 i 25 Interchange circuit Name Transmitted data Received data Ready for sending Data set ready Data terminal ready Calling indicator 4.1.1.1 Circuit 103 - Transmitted data - Direction from D
34、CE X X X X to DCE X X The instructions issued by the DTE during the automatic calling procedure, known as commands, are transmitted to the DCE on this circuit. 4.1.1.2 Circuit 104 -Received data Responses from the DCE to DTE Commands, known as indications, are transmitted to the DTE on this circuit.
35、 Optionally, circuit 104 may convey the echo of the commands transmitted on circuit 103. 4.1.1.3 The DCE shall turn circuit 106 ON in response to the DTEs circuit 108/2 being ON. The DCE shall turn circuit 106 OFF: Circuit 106 -Ready for sending i) ii) on connection to line when answering tone is de
36、tected; when the DCE aborts the call Set-up under the control of DTE by turning 108/2 in the OFF condition. 4.1.1.4 The DCE shall turn circuit 107 ON: Circuit 107 -Data set ready i) ii) at the end of the automatic call Set-up procedure, to indicate to the DTE that the connection is established and t
37、he DCE connected to line; on completion of manual call Set-up procedure. The DCE shall turn circuit 107 OFF: i) ii) to indicate to the DTE that the connection has been cleared down during the data transfer phase (to be permitted where national regulations require it); in response to a clear request
38、by the DTE turning OFF circuit 108/2. Recommendation V.25 bis (10/96) 3 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesSTD-ITU-T RECMN V-25 BIS-ENGL L99b 48b259L Ob27213 TTq = 4.1.1.5 The DTE turns circuit 108/2 ON: Circuit 108/2 -Data
39、 terminal ready i) ii) to enable the DCE to set up a connection either manually or automatically; to indicate to the DCE that it is ready to accept an incoming call. The DTE shall turn circuit 10812 OFF: i) to instruct the DCE to clear down the connection during data transfer; ii) to instruct the DC
40、E to abort the call Set-up procedure; iii) to indicate to the DCE that it is not ready to accept an incoming call. 4.1.1.6 Circuit 125 -Calling indicator The DCE shall provide circuit 125 to indicate to the DTE an incoming call. This incoming call will override a call request prior to seizure of the
41、 line. The usage of circuit 125 in the DTE is optional. 4.1.1.7 Other interchange circuits The state of other interchange circuits is not part of the procedure. However, to ensure maximum compatibility with existing equipment, the other interchange circuits provided should retain their normal functi
42、on during the automatic calling procedure. Particularly to ensure correct operation of the DTE, the condition of circuit 109 shall follow the condition of circuit 106. The DTE may choose to hold circuit 105 ON during the automatic calling procedure, but the DCE is not required to recognize this cond
43、ition. 4.1.2 Control information format Call Set-up is achieved by the use of interchange circuits 106, 107 and 108 together with messages exchanged between the DTE and the DCE on circuits 103 and 104. These messages consist of commands or indications from the DTE or DCE respectively, and may be acc
44、ompanied by parameters where necessary. The commandshdications required for the automatic calling procedure are outlined in Tables 2 and 3 together with their parameters. The use of commandshdications other than one of the call request commands (CRJ and the invalid indication (INV) is optional in th
45、e DTE and DCE respectively. The comandshdications and their parameters are described below. 4.1.2.1 Call request commands These commands from the DTE instruct the DCE to initiate a call Set-up procedure. The commands shall include a suffix to indicate the type of call request concerned (see Table 3)
46、 and shall be accompanied by one or more of the following parameters: i) the number to be dialled. (In applications where additional dial tones are required, separators, “wait tone”, etc., may be included in this number); ii) the identification number of the data station; iii) the DCE memory address
47、 which contains the number to be dialled, this having been previously programmed. NOTE -Manufacturers should note that the response time to a Call Request Command is determined by the time required to execute line procedures (see 6.1). 4.1.2.2 Program commands These commands from the DTE instruct th
48、e DCE to enter a programming state. The commands shall be accompanied by one or more of the following parameters: i) the DCE memoxy address into which the number to be dialled is to be stored; ii) the number which is to be stored; iii) the identification number of the data station. 4 Recommendation
49、V.25 bis (10/96) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services- STD*ITU-T RECMN V-25 BIS-ENGL L99b D YAb2591 Ob27214 730 Where a DCE does not contain the programming capability, this DCE shall reply to a program command by an invalid indication. Where a DTE is not capable of programming the DCE, it may still initiate call attempts using the call request command in the normal way. 4.1.2.3 List request commands These commands from the DTE instruct the DCE to list the numbers that have been pro
