Chapter 5: Configuration56 ISU 512 User Manual 61202.086L1-1CONFIGURING THE ISU 512 FOR V.25 BIS IN-BAND DIALINGV.25 bis dialing is used primarily by data terminal equipment with synchro-nous interfaces (HDLC/SDLC or BSC/BISYNC) not supporting the AT com-mand set, which is commonly used by asynchronous devices. The ISU 512supports V.25 bis in-band dialing in accordance with Fascicle VIII.I - V.25 bis(Malaga-Torremolinos 1984, Melbourne 1988).Recommendation V.25 uses the following DCE/DTE control signals:Transmitted data Circuit 103Received data Circuit 104Ready for sending Circuit 106Data set ready Circuit 107Data terminal ready Circuit 108/2Calling indicator Circuit 125The ISU 512 supports the following V.25 bis commands to control automaticcalling and answering:CRN Call request (number in command)CRS Call request (using stored number)PRN Program stored numberRLN List stored numberCIC Connect incoming callDIC Disconnect incoming callWhen using stored numbers, V.25 bis accesses stored numbers 1 through 9 used byfront panel dialing. See Dialing Options (in this chapter).Auto answer should be disabled if V.25 bis is in control of answering incoming callswith the CIC/DIC commands, since the other settings for Auto answer will overrideV.25 control of the answer function.
