ISDN Data and Telephony Protocol Engine (inc. X.25)
CMX228
Digits received before the network has returned the SETUP ACK message are saved. Upon receipt of
the SETUP ACK any saved digits will be transmitted.
The DTMF tone mapping is as shown below:
Low Group
(Hz)
High Group (Hz)
1336
2 (32)
5 (35)
8 (38)
1209
1 (31)
4 (34)
7 (37)
S (2A)
1477
3 (33)
6 (36)
9 (39)
# (23)
1633
697
770
852
941
A (not used)
B (not used)
C (not used)
D (not used)
0 (30)
Once the network has indicated that the full number has been received, no further digits will be sent to
the network. All tones and announcements from the network (eg ringing, NU, busy etc) and audio (if
the call is connected) will be routed to the POTS port, until that port goes on-hook.
1.5.5.4 Connected Calls
Once a call is connected to the analogue port, whether it was incoming or outgoing, a LED indicator
pin is set high to indicate that the call is connected. See section 1.5.9.1 for details of the LED
indicator pins. Once the call is disconnected, either by receipt of a DISCONNECT message from the
network or an on-hook indication, that LED indicator pin is set low.
During a call, if a Recall (ie a line break of appropriate length) is received from the POTS port, the
CMX228 will start to look for DTMF tones received on the POTS port. Any tones received will then be
sent to the network in ISDN INFORMATION messages, as Keypad Information Elements.
1.5.5.5 Call Clearing
The call is cleared either by the port going on-hook or by the ISDN network. Note that the ISDN B-
channel which was being used is not released until the POTS port has gone on-hook.
ã 1999 Consumer Microcircuits Limited
ã 1999 Chiron Technology Limited
16
D/228/1
CMLMICRO [ CML MICROCIRCUITS ]
