ISDN Data and Telephony Protocol Engine (inc. X.25)
CMX228
1.5.7 Data Operation
1.5.7.1 Incoming B-Channel Data Calls
All incoming data calls which have valid channel use and MSN are directed to the data port and cause
‘RING’ followed by the digits of the calling party number and the calling party subaddress (if received
in the SETUP message) to be returned to the DTE. The Ring Indicator (RI) pin is also raised, then
lowered after 3s. ‘RING’ text and the raising of RI for 3s is repeated every 6s until the call is cleared
or answered, provided S0=0. If S0=1 then only one RING will appear at the DTE and the RI line will
be raised only once, as a CONNECT message will be sent to the network.
1.5.7.2 Outgoing B-Channel Data Calls
Outgoing calls are requested specifying either B-channel unless channel mapping is enabled via !C4
and !C5 registers. The SETUP message is sent without High Layer Compatibility or Low Layer
Compatibility and with the following Bearer Capability:
CCITT coding standard
Unrestricted digital
Circuit mode
64k information transfer rate
If there is a saved MSN in !C6 register all outgoing call SETUP messages will contain the saved
number in a Calling Party Number Information Element.
1.5.7.3 X.25 Data Calls on the D-Channel
When D-channel data is selected (via Hayes register %A2), B-channel data calls cannot be made.
Any incoming B-channel data calls will be rejected with ‘Busy’.
1.5.7.4 Connected Calls
Once a call is connected to the digital port, whether it was incoming or outgoing, the DCD pin is set
high to indicate that the call is connected (providing &C0 command is not given). If the DCD pin is set
high, the LED3 pin will be set low.
1.5.7.5 Call Clearing
The call is cleared either by the ATH command or by the ISDN network. When the call has been
cleared, the DCD pin is set low and the LED3 pin is set high (providing the &C0 command is not
given).
ã 1999 Consumer Microcircuits Limited
ã 1999 Chiron Technology Limited
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CMLMICRO [ CML MICROCIRCUITS ]
