1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 1 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU).4%27/2+).G0G0/b) there is no necessity to modify existing equipment to provide charge/no charge information transfer capabilities.From a technical viewpoint, international no charge calls are possible witho
2、ut restrictions only when the SignallingSystems No. 6, No. 7 (TUP) or R2 are used exclusively throughout the entire international network (assuming that no chargeinformation is received from the national network).In the case of interworking with systems not able to transfer the no charge information
3、, a no charge call can atpresent only be provided by withholding the answer signal. Consequently the transfer of no charge information must not beperformed in these cases.In the case of Signalling System No. 6, the information no charge should be sent together with the address-complete,no charge. If
4、 this information is contradicted by the subsequent answer, charge signal the call should nevertheless not becharged ( 4.1.9, Signalling System No. 6 specification).The transfer of no charge information is possible when interworking:from any of the Signalling Systems: No. 61), No. 7 (TUP)1)and R2 to
5、 any of the Signalling Systems: No. 6, No. 7(TUP) and R2.1)When interworking from Signalling System No. 6 or No. 7 (TUP) to Signalling System R2 the comments of 8.1 have to be taken intoaccount.2 Fascicle VI.6 - Rec. Q.6088.2 Time-out guidelines8.2.1 Time-outs connected with subscribers behaviourThe
6、 specified register time-out of 4 to 6 seconds (after each digit is received which is resorted to when addresscomplete cannot be identified in another way) has proved to give satisfactory technical functioning at least in those caseswhere the exception described in Recommendation Q.261, 4.1.5, e) do
7、es not apply.Insufficient information is obtained to motivate a change at this stage of the duration of the 4 to 6 seconds time-outspecified in the outgoing register in cases where no address-complete indication is available.It is recommended that the 4 to 6 seconds interdigital time-out procedure s
8、hould be used where needed only. It isfurthermore recommended that Administrations make their network numbering known to their respondents so that maximumuse of number length analysis can be made whenever address-complete information cannot be given.8.2.2 General time-out guidelines for new signalli
9、ng systemsi) 20-30 seconds is considered to be the proper time-out interval for outgoing registers for non-receipt of addresssignals, or address complete.ii) When backward signals are provided, if the address-complete signal is not available before 15-20 seconds afterthe last received address signal
10、 at the incoming register, then an address incomplete signal should be sent. If,however, it is known that the address is complete, then the time-out should be extended to 20-30 seconds.iii) If it is known that a positive (real) address-complete signal is available but will not be returned within the
11、 lowerlimit of the 20-30 second time-out period of the outgoing register then an artificial address-complete signalshould be sent within 15-20 seconds. The indiscriminate use of such a signal should be avoided. A new “call-in-progress“ signal should not be used instead of the “artificial address-com
12、plete“ signal.iv) When backward signals are not available and complete number length analysis in the outgoing register is notpractical, then the 4-6 seconds time-out is used to determine address complete instead of the 20-30 seconds time-out mentioned in point i). This time-out commences when the mi
13、nimum number length has been reached. Thenumber length is determined when the time-out matures or if the known maximum number length is received.8.2.3 General time-out guidelines for existing signalling systemsThese guidelines are primarily intended for signalling on international calls where fully
14、overlap digit sending canoccur. Other guidelines may be appropriate to some national applications.During call set up both incoming and outgoing registers are normally supervised by timers. The duration of the time-out interval is defined in the relevant Recommendations defining the signalling system
15、s. These are summarised in the tablebelow. In the case of a multi-link connection with overlap signalling, the time between digit transmission or reception will besupervised at each exchange, and according to existing Recommendations, at both incoming and outgoing registers in eachexchange. It is co
16、nsidered that this situation is unsuitable since the cleardown of a call where insufficient digits are dialled canlead to unpredictable results because of the possibility of timers expiring in a different order on subsequent call attempts. Insome cases this can lead to different tones being returned
17、 to the calling subscriber on subsequent calls. Since the first to expireand therefore normally the controlling time-out will be the incoming register time-out of around 15-20 seconds, it isrecommended that this time-out should only be activated at a single point in the connection at any stage of ca
18、ll set up. Themost suitable point is the incoming register at the exchange closest to the called subscriber at any point in the call set up. Toachieve this it is recommended that the incoming register time-out should be inhibited at each exchange once the outgoingcircuit has been seized. The longer
19、time-out of around 20-30 seconds which will be active at outgoing registers, and in somecases incoming registers also, should not be inhibited.This feature need not be implemented at existing exchanges or for Signalling System No. 4 which has time-outs not inconformance with modern practice.Fascicle
20、 VI.6 - Rec. Q.608 38.2.4 Summary of inter-digital time-outsType of time-outSignalling System4567R1R2Outgoing 15-30 sQ.127 4.4.1.2a.220-30 sQ.268 4.8.5.1 (a)20-30 sQ.724 6.4.1 24 sQ.476 5.5.1.2IncomingReceipt of digit30-60 sQ.127 4.4.3(2)a10-20 s(to KP signal)20-40 stypical (toST signal)Annex 2Table
21、s 4 and 615-20 sQ.261 4.1.615-20 sQ.724 1.710-20 s(to ST signal)Q.325 3.6.2.28-24 s(15-24 s)(preferred)Q.476 5.5.2.1OutgoingDetermination ofST condition4-6 sQ.152 3.2.14-6 sQ.321 3.2.1b(ii)IncomingTime-out afterST received20-30 sQ.268 4.8.5.3 (a)20-30 sQ.724 6.4.3 (a)8.3 Reset procedures8.3.1 When t
22、he reset signal is received on an incoming Signalling System No. 6 or 7 (TUP) circuit the succeeding circuit isreleased by the clear-forward procedure in all cases.8.3.2 When the reset signal is received on an outgoing Signalling System No. 6 or 7 (TUP) circuit the response is:i) to initiate the cle
23、ar-forward sequence on the outgoing circuit;ii) to release exchange equipment as appropriate, i.e. SPITE 3 in the register phase and SPITE 5 in the speechphase;iii) to return an appropriate signal and/or tone on the incoming circuit as shown in the following table.4 Fascicle VI.6 - Rec. Q.608SignallingSystem No.Register phase Wait for answer Answered Clear-back4 Busy flash Busy flash5 Busy flash Busy flash6 CFL CFL Clear-back + Congestion tone7 (TUP) CFL CFLcongestiontone if possibleif possibleR1 Congestion tone Congestion toneR2 A4/B4 Congestion tone
