CMX208S1 MX-COM, Inc., CMX208S1 Datasheet - Page 13

• Manufacturer Part Number: CMX208S1
• Description: ISDN dual telephony protocol engine
• Manufacturer: MX-COM, Inc.

ISDN Dual Telephony Protocol Engine
Once the ‘$’ has been recognized, each digit pressed is then checked for validity as a configuration
sequence. If any digit pressed is not a valid configuration digit, all digits pressed so far will be transmitted to
the network in INFORMATION messages as Keypad Information Elements, until a ‘ ’ is entered (with the
exception of ‘$ ’ being entered, see Keypad Operation below). If the first four digits received are a valid
configuration sequence then the configuration mode is entered. When a valid configuration has been
completed the CMX208 will send a single DTMF tone to the POTS port. If a valid configuration sequence is
received but subsequent digits are invalid, then subsequent digits entered will be ignored and two DTMF
tones will be sent to the POTS port.
If the port goes on-hook part way through configuration, it will cause any digits received so far to be ignored.
Configurations can be performed consecutively with the exception of the test function (where the attached
handset must be replaced immediately after the configuration has been audibly signaled to the POTS port).
All configurations entered will be retained after a power-down as they are stored in the external EEPROM.
4.5
4.5.1
The CMX208 supports ISDN keypad messages for control of Network Supplementary services either before
or during call establishment. When dialing a number (i.e. off-hook and dial tone audible on POTS port), or if a
call has been disconnected by the network but the POTS port has not yet gone on-hook, any keypad string
entered will be sent to the network as ‘Keypad Information Elements’ within INFORMATION messages.
Keypad strings are defined as the following sequences of digits, with the exception of the configuration strings
defined in the previous section:


When a call is connected, pressing the recall key results in all subsequent key presses being sent to the
network as ‘Keypad Information Elements’ within INFORMATION messages, until the handset is replaced.
The tones generated by the key presses are also passed down the B-channel, so the remote user will be able
to hear them.
4.5.2
An incoming POTS call is identified by the Bearer Capability Information Element of the SETUP message
being set to ‘Speech' or ‘3.1kHz Audio’. The call will be routed to either (or both) of the POTS ports which
satisfy the following three conditions:
When the call is routed to a port, the ringing signal for that port will be applied by means of the RING1 and
The call is answered when either of the ports with ringing signal goes off-hook. The ringing signal is then
stopped and the ISDN call is connected to that port.
4.5.3
Outgoing calls are initiated when a POTS port goes off-hook. An ISDN SETUP message is sent to the
network with the Bearer Capability Information Element set to 'Speech'. The dial tone presented by the
network on that ISDN B-channel which was selected by channel mapping (See Section 4.3.6), will be routed
to the POTS port initiating the call.
When DTMF tones are received from the POTS port, they are sent to the network either as Called Party
Number or Keypad Information Elements. Keypad Information Elements are discussed in Section 4.5.1.
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RING1 (or RING2 and
The port is on-hook.
The MSN saved for the port matches the Called Number in the incoming SETUP message, or no MSN is
specified for the port, or there is no Called Number in the SETUP message. See Section 4.3.5 for details
of POTS port MSN selection.
The ISDN B-channel on which the call is placed (as indicated in the SETUP message) is compatible with
the channel mapping configuration for the port. See Section 4.3.6 for details of POTS port channel
mapping selection.
POTS Operation
Keypad Operation
$...
$ ...
Incoming POTS Calls
Outgoing POTS Calls
...
RING ) pins.
2
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2000 Chiron Technology Limited
CMX208 Advance Information
Doc. # 20480214.001
2000 MX-COM, Inc.