1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 ) TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU).4%2!4%$G0G03%26)#%3G0G0$)4!,G0G0.%47/2+)3$.G93%26)#%G0G0#!0!“),)4)%3#!,G0G0/&%2).G0G03500,%-%.4!293%26)#%3G0G0G13G0G0,).%G0G0(5.4).G0G0 ,(G9)45G134G0G0RecommendationG0G0) (Extract from the “LUEG0“OOK)NOTES1
2、 ITU-T Recommendation I.252.6 was published in Fascicle III.7 of the Blue Book. This file is an extract fromthe Blue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, thecontents of the file are identical to the Blue Book version and copyrigh
3、t conditions remain unchanged (see below).2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both atelecommunication administration and a recognized operating agency. ITU 1988, 1993All rights reserved. No part of this publication may be reproduced or utiliz
4、ed in any form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle III.7 - Rec. I.252.6 1Recommendation I.252.6Fascicle III.7 - Rec. I.252.6CALL OFFERING SUPPLEMENTARY SERVICES - LINE HUNTING (LH)(Melbourne, 1988)6 Line
5、Hunting6.1 DefinitionLine Hunting is a supplementary service which enables incoming calls to a specific ISDN number to bedistributed over a group of interfaces.Note - Development of Line Hunting to cover the case of hunting on available ISDN numbers, or addresses,rather than on interfaces is a possi
6、ble extension of the service.6.2 Description6.2.1 General descriptionThe interfaces selected for Line Hunting may be contained within one node, or may encompass more than onenode.It is the responsibility of the user to provide terminals to his interfaces for effective operation of the service.The pr
7、oblem of terminal compatibility in the Line Hunting supplementary service is also the responsibility of the user ofthe service.6.2.2 Specific terminologyThe following specific terminology is used to describe the possible selection method:Sequential hunting A sequential search is conducted over theme
8、mbers of the group in a fixed pre-specified orderUniform distribution An equal distribution of calls is provided toidle members of the groupThe actual algorithm for each hunting method is a network provider option.Note - The status of an individual channel may be included in the selection criteria a
9、bove.The selection of an interface is based on the availability of information channels rather than on the NDUBstatus. As part of each applicable bearer service or teleservice, there is already an option specifying the maximumnumber of information channels which can be used on the interface for each
10、 ISDN number, all ISDN numbers or subsetsof ISDN numbers.6.2.3 Qualifications on the applicability to telecommunication servicesThis supplementary service is considered meaningful when applied to the speech and 3.1 kHz audio bearerservices and to the Telephony teleservice. Furthermore, it may also b
11、e meaningful when applied to other services.6.3 Procedures6.3.1 Provision/withdrawalLine Hunting is offered, with possible subscription options, as a service to the called party and applied to anISDN number. For each subscription the following are specified:Subscription options ValuesSelected Method
12、 Sequential UniformMembers List of 2 or more interfaces2 Fascicle III.7 - Rec. I.252.66.3.2 Normal procedures6.3.2.1 Activation/deactivation/registrationLine Hunting is activated on provision and deactivated on withdrawal.6.3.2.2 Invocation and operationAn incoming call to an ISDN number on which Li
13、ne Hunting is in operation will be offered to a specificavailable interface in a pre-defined manner. The selection of the specified interface may provide for a uniformdistribution of calls or sequential distribution of calls.The method of selecting the interface may be either Sequential Hunting or U
14、niform Distribution. The selectionalgorithm may include reference to the channel status.Once an interface has been selected, normal call set-up procedures apply and Line Hunting procedures areconsidered complete.Outgoing calls from a Line Hunting Group are unaffected by this service.6.3.3 Exceptiona
15、l procedures6.3.3.1 Activation/deactivation/registrationNone identified.6.3.3.2 Invocation and operationIf no interface is available, the Line Hunting service is unsuccessful and a busy indication is returned to thecalling subscriber.If no compatible terminal on a selected interface responds, no fur
16、ther line hunting action is provided and thecall is released in the normal manner.If the offered call is rejected at an interface, the call is released with normal procedures. No further hunting isprovided.6.3.4 Alternative procedures6.3.4.1 Activation/deactivation/registrationNone identified.6.3.4.
17、2 Invocation and operationNone identified.6.4 Network capabilities for chargingThis Recommendation does not cover charging principles. Future Recommendations in the D-Series areexpected to contain that information.It shall be possible to charge the subscriber accurately for the service.6.5 Interwork
18、ing requirementsThe possibility of a line hunting group including both ISDN and non-ISDN interfaces for a particular LineHunting service should be considered. This is for further study.6.6 Interaction with other supplementary services6.6.1 Call WaitingThe Call Waiting service should not be provided
19、to a line in a hunt group.6.6.2 Call TransferNo impact, i.e. neither supplementary service affects the operation of the other supplementary service.6.6.3 Connected Line Identification PresentationNo impact, i.e. neither supplementary service affects the operation of the other supplementary service.6
20、.6.4 Connected Line Identification RestrictionNo impact, i.e. neither supplementary service affects the operation of the other supplementary service.Fascicle III.7 - Rec. I.252.6 36.6.5 Calling Line Identification PresentationNo impact, i.e. neither supplementary service affects the operation of the
21、 other supplementary service.6.6.6 Calling Line Identification RestrictionNo impact, i.e. neither supplementary service affects the operation of the other supplementary service.6.6.7 Closed User GroupWhen a free line of a Line Hunting Group has been found, any CUG restrictions must be met before the
22、connection will be established.6.6.8 Conference CallingNo impact, i.e. neither supplementary service affects the operation of the other supplementary service.6.6.9 Direct-Dialling-InNo impact, i.e. neither supplementary service affects the operation of the other supplementary service.6.6.10 Call Div
23、ersion (i.e. Call Forwarding) services6.6.10.1 Call Forwarding Busy (CFB)If the outcome of the Line Hunting supplementary service is unsuccessful (see 6.3.3.2 above), CFB may beinvoked.6.6.10.2 Call Forwarding No ReplyNo impact, i.e. neither supplementary service affects the operation of the other s
24、upplementary service.6.6.10.3 Call Forwarding UnconditionalWhen the CUF and Line Hunting supplementary services are both subscribed to on the same ISDN number,the CFU supplementary service takes priority. Further information is contained in the CUF definition in 4.6.6.11 Line HuntingNot relevant.6.6
25、.12 Three-Party ServiceNo impact, i.e. neither supplementary service affects the operation of the other supplementary service.6.6.13 User-to-User SignallingNo impact, i.e. neither supplementary service affects the operation of the other supplementary service.6.6.14 Multiple Subscriber NumberFor furt
26、her study.6.6.15 Call HoldNo impact, i.e. neither supplementary service affects the operation of the other supplementary service.6.6.16 Advice of ChargeNo impact, i.e. neither supplementary service affects the operation of the other supplementary service.6.7 Dynamic descriptionThe dynamic description of this service is contained in Figure 6/I.252.4 Fascicle III.7 - Rec. I.252.6FIGURE 6/I.252Line hunting overall SDL
