Patent GB-270068-A (GB)
Title: Improvements relating to the metering of calls in automatic telephone systems
IPC: H04Q3/00
Filed: 1926-04-01
Abstract: 270,068. Siemens Bros. & Co., Ltd., and Humphries, H. E. April 1, 1926. Automatic exchange systems; metering.-In a system in which the normal metering operation is initiated on the reply of the called party, a second metering operation takes place upon release if the connection includes a trunk for which an additional fee is charged. In the arrangements described, the answering supervisory signal consists in the connection of battery to the a-wire of the trunk, and the additional metering signal consists in one arrangement in the connection of battery to the b-wire, and in the other arrangement in the prolongation or reapplication of the answering supervisory signal. Delayed metering apparatus is provided of the kind described in Specification 200,928, comprising relays S, Z and a rotating cam interrupter. First arrangement, Figs. 1 and 2. When the called subscriber replies, relays YY, HH energize at the incoming selector, Fig. 2, and the former connects battery to the a-wire of the trunk to energize relays Y, H at the first selector, Fig. 1. Relay Y causes the relays S, Z to operate in the usual manner to close the metering circuit over contacts s1, z1, but relay Z remains locked up over contacts z4, v1. When the calling party hangs up, relays A, AA falls back, a relay J is connected to the b-wire, and relay M energizes, connecting a charged condenser Q to relay B, which pulls up and connects battery to the b-wire to energize relay J, which locks and short-circuits its energizing winding to delay release. Release relay V on relapsing completes the metering circuit again over contacts v4, j3, z1, and relay Z falls back slowly, disconnecting relay J. A busy condition causes an intermittent operation of relays YY, Y which is insufficient to effect metering. In the case of a call to an operator's position, relay HH only is energized by weak current fed back, and battery over a resistance and relay HA is connected to the a-wire to operate relay H only. Relay H, HA control holding circuits for release relays V, VV. Second arrangement, Figs. 3 and 4. Answering supervisory relay YY at the incoming selector, Fig. 4, connects battery to the a-wire of the trunk to energize relay Y at the first selector, Fig. 3, which effects metering by means of relays S, Z. When the calling party hangs up, relays A, AA fall back, and release relay VV upon relapse connects battery through relay HA to the a-wire to prolong the answering supervisory signal after relay YY falls back. Relay HA energizes and holds up an additional release relay VB. Relay Y therefore remains operated (or reoperates if the called party hangs up first), and release relay V upon release opens the locking circuit of relay Z, so that a second metering cycle ensues, but an additional release relay VA holds over contacts y3, l2, va4. Relay Z connects up relay L, which energizes, holding up relay Z, and disconnects release relav VA, and the switch restores. Relay HA falls back and opens the circuit of release relav VB. If the called party does not reply, relay L remains energized, and when the calling party hangs up and relay V falls back, relay Z energizes over contacts v4, l5, va5 and locks relay L, so that there is no holding circuit for release relay VA. Release occurs without metering therefore. In a modification of this arrangement, relay Z remains locked after the first metering operation over a contact of relay VA, and the metering circuit is closed a second time due to the re-energization of relay L upon the relapse of release relay V. Relays VA, Z then fall back.