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Fig-3 Charging principles Zone charging centre Zone boundary Zone to zone calls Base rate calls {A, B) digits allotted to them, are shown in Figure 2, which also shows the charging centre for each charging area. The principle of charging is that the charge should be based upon the distance between the charging centres of the tariff zones in which the calling subscriber and the called subscriber are situated. Figure 3 shows this principle. Calls are periodically metered on a modified Karlsson basis which means that periodic pulses, the pulse period depending upon the distance between charging centres, are applied to the calling subscriber's meter. Calls within a charging area are metered with the maximum pulse period. Concessional rates are provided for calls made between 6 p.m. and 9 a.m., except in the case of calls not exceeding 100 miles between charging centres. The Australian system uses four periodic metering rates and a no-charge rate. Some categories of calls, such as calls to the printergram service (which permits transfer between the telex network and the public telegram network and therefore is of advantage to the Administration), calls to service positions, such as manual assistance, complaints, and directory enquiries are, of course, not charged and the equipment is arranged to take account of this requirement. The table of pulse periods for the various rates is shown in Table 2. Each pulse represents a 5-cent Australian charge. Tublc 2: Meter pulsing rates A feature of the Australian charging method is that the calling subscriber is able to check the answer-back returned from the called subscriber's machine without charge, since the commencement of metering is inhibited for a period of 5-10 seconds. As the automatic telex system itself calls for answer-back, a subscriber has the opportunity in this period to observe an incoming answerback and immediately clear if he has not obtained the correct connection, thus avoiding charging. After this inhibition period, regular pulses randomly phased with respect to the commencement of the call are applied to the subscriber's meter. 24
Fig. 4 The Australian automatic telex network, June 6th 1967 ARM transit exhange ARB terminal exchange Tntertransit trunks Terminal to transit trunks Equipment installation provides for this number of subscribers lines Type of Switching System The system chosen for Autralia, after examination of world-wide tenders, was the L M Ericsson ARB 10 system which consists basically of trunk exchanges of the ARM 20 or ARM 50 type with appropriate telegraph repeaters and registers working in conjunction with specially developed telegraph exchange subscriber stages known as ARB 111. Figure 4 shows the general network provided at 30.6.67. Terminal exchanges ARB 111 have a maximum size of 400 lines, and a typical complete exchange installation such as that at Sydney consists of an ARM transit exchange of 600-line capacity to which are connected subscriber stages with a line capacity of 1,320 subscribers. The subscriber stages are provided as four 400-line dependent ARB 111 exchanges (the fourth being incomplete) on the same exchange floor, together with an 80-line ARB 111 exchange remotely located at Newcastle and with the capability of connecting many other dependent exchanges at various provincial centres as well as providing additional 400-line blocks in Sydney itself. Type of Signalling System The subscriber selection signalling system using the teleprinter keyboard was chosen for the Australian network mainly because of the advantages in speed of signalling and in the cheapness of subscriber terminal units arranged for this type of subscriber selection signalling. Printed service code supervision is used with the following codes OCC DER ABS NA NC NP MOM Subscriber Busy Out of Order Subscriber Absent - or Office Closed Connection Not Admitted No Circuits, or Trunks Busy Not a Working Line Wait The C.C.I.T.T. Type B signalling system was chosen for Australian trunk telegraph operation as described in another article in this issue. 25
Page 1: 1 1968
Page 4 and 5: Stored Program Controlled Telephone
Page 6 and 7: Signalling in L M Ericsson Telex Sy
Page 8 and 9: On physical subscriber lines other
Page 10 and 11: In a new Recommendation U 11, CCITT
Page 12 and 13: Automatic Tripping of B Subscriber'
Page 14 and 15: egister in ARM selects a new circui
Page 16 and 17: show the signalling both for single
Page 18 and 19: Fig. 11 gnalling for setting up a c
Page 20 and 21: In this case, after receipt of the
Page 22 and 23: Similar intervvorking exists with t
Page 24 and 25: The capital cost of the telex syste
Page 26 and 27: Fig. 1 Traffic distribution by dist
Page 30 and 31: Transmission Considerations The obj
Page 32 and 33: A variety of special subscriber mar
Page 34 and 35: to be tripped. The calling subscrib
Page 36 and 37: References 1. C.C.T.T. Illrd Plenar
Page 38 and 39: Corrugating Machine The aim in the
Page 40 and 41: Laying The corrugated duct may have
Page 42 and 43: New Factory Opened at Ostersund L M
Page 44 and 45: Dirivox and Centrum in the Soviet U
Page 46: The Ericsson Group Associated and c

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