Incoming Call Sample Clauses
Incoming Call. Modem pool dialling with incoming calls is only possible for trunk lines which support Direct Dial In (DDI). If DDI is not possible, the call is routed to the operator or a Permanent Line Extension and modem pool dialling is not used. A call to a PLE can be routed to a modem which is determined by the CV matrix (route CV/PLE CV). If a modem in the modem-pool is idle, all signals between the MLU and the modem are in the off-condition. Call processing detects an incoming call over an analogue trunk line (with CV) via the line signals. The ISPBX retrieves the required destination number by the register signalling. This number indicates a destination party to which a compatibility value is assigned. The compatibility check between the trunk-CV and the destination-CV is used to find out whether the party is a data party and which type of modem must be used for the connection. Now a free circuit on a MLU with the correct modem type is seized. Two data paths are established through the switching network: - From the ATU circuit to the MLU: The analogue input signal from the trunk line is digitised (A/D convertor) on the ATU board into a standard 64 kbps signal. This digitised analogue signal is sent to the MLU, via the switching network, in the USO-line. The analogue signal is retrieved from the USO line and sent to the modem. - From the MLU to the destination party: After demodulation the resulting user information is sent back in V.24 format to the MLU. The V.24 user information is transferred to the internal party, via the data rate adaptor, in 64 kbps format in a timeslot in the USI-line. The user information is retrieved and transferred to the SOPHO-SET, SOPHO-▇▇▇ or ▇▇▇, via the related DLC circuit, in a 64 kbps signal. Here the V.24 user information is retrieved from the 64 kbps signal and sent to the data party. For full duplex data communication, the reversed path must also be established through the switching network. Call processing sends ringing current to the destination party and starts waiting for the answering of the call. The call establishment is guarded by timers. When the destination party answers the call, manually or automatically, the pool-modem is activated: - CT108.1 (CDSL) forces the modem on-line. - CT111 (DSRS) is sent to the modem to indicate if the high or the low speed must be used- depending on the projecting of the MLU-circuit. - CT126 (STF) is set in the on-situation to indicate the modem must send in the high- frequency band and ...
Incoming Call. For an incoming call over a leased line, the procedure is quite different from the convertor situation. Because there is no way of detecting an incoming call when the line is connected to the telephone set (unattended modem), the CDSL (CT108.1) signal must be continuously active. The modem is continuously connected to the telephone line. The CT107 signal (DSR) is returned to the MLU to indicate the modem is connected to the telephone line. An incoming seizure on the MLU circuit is only possible if the circuit is projected for NO constant carrier-see Projecting Aspects. If the pool-modem is idle and detects an incoming carrier, the signal DCD (CT109) to the MLU is activated and the MLU circuit sends a message to the SOPHO-S2500 CPU to indicate an incoming seizure. If the send and receive frequency of the modem is controlled by the MLU by signal CT126 (STF), the incoming carrier can only be in the high frequency band. If the modem is idle the signal CT126 is in the off-condition. The modem is in the calling mode and detects only the carrier in the high-frequency band. If the send and receive frequency is controlled by the modem itself (switches and/or straps) the incoming carrier can be in the high (modem in calling mode) or in the low (modem in answering mode) channel. After the incoming seizure the pool-modem is inserted into the call processing state. Over a leased line NO dialling information can be received by the modem and call processing does not receive any indialling information: the leased line behaves like a trunk line without DDI. Normally the call will be routed to an operator A-queue (incoming route option) but with digital information this will not be very useful. Another option is to assign a Permanent Line Extension (digital party) to the `trunk' lines in this route. This PLE-data terminal (can also be a group of terminals) answers the incoming calls over the leased line. DDI with digit conversion to a complete number can also be used. One data path is established through the switching network: - From the MLU to the PLE: The analogue (modulated) signal now enters directly on the modem. The demodulated user information is sent in V.24 format to the MLU and the data rate adaptor incorporates the user information in the 64 kbps standard signal. The 64 kbps signal arrives at the SOPHO-SET, SOPHO-▇▇▇ or ▇▇▇ (via the switching network and the DLC circuit). This device retrieves the user information from the 64 kbps signal and sends it to the data ...