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CMX208

ISDN Dual Telephony Protocol Engine

MX-COM Inc  

ISDN Dual Telephony Protocol Engine

10

CMX208 Advance Information

4.2 Initialization

On power-up, the CMX208 assumes its default values, which are factory programmed into the firmware. It

then performs a self-test, during which all of the LED pins and the ILFI pin are held high for 3 seconds. If the

test is unsuccessful, the CMX208 remains in this condition.

If the test is successful, the CMX208 reads its preset values from the attached EEPROM and examines the

state of the ISDN link (i.e. Layer 1) before commencing normal operation. On power-up, the ISDN link is de-

activated; the POTS ports are assumed to be on-hook and ringing is disabled.

4.3 ISDN Interface

Two simultaneous voice calls are possible. Incoming calls are firstly checked for other calls present, then the

MSN is checked for validity, then the channel mapping, so that responses will be handled accordingly.

When channel mapping is enabled, outgoing calls will request the channel enabled. When not enabled, a

request for any channel is made. If no free channels are available for outgoing calls, a locally generated busy

tone is returned to the analog port.

4.3.1 Activation

Activation occurs in the following circumstances:

• The ISDN network activates.

• The device connected to the analog port goes off hook.

The Terminal Endpoint Identifier (TEI) is negotiated. Line powering of the CMX208 is not supported.

The 'AR' indicator (LED8) toggles between high and low states when the CMX208 is powered up, and

remains constantly low once the CMX208 identifies an activated ISDN line.

ISDN line power detection is not implemented and the CMX208 will negotiate a new TEI on any new network

activation.

4.3.2 De-activation or Line Disconnection

De-activation or line disconnection causes the TEI to be removed. Upon re-connection the CMX208 will only

be re-activated and request a new TEI when one of the conditions in the above section is met.

4.3.3 Line Failure Detection

If the line failure detection parameter is enabled (via either POTS port) the CMX208 will check that Layer 2

communications are active every sample period of 30 seconds. If Layer 2 communications are not active, the

CMX208 will attempt to activate them. If they remain inactive for 2 sample periods, the line is deemed to

have failed, so then the ILFI pin is set high and RING1, RING1, RING2 and RING2 pins are set low. The

CMX208 continues to attempt to activate the line and if it becomes active and stays active for 2 sample

periods, then the ILFI pin is set low and RING1, RING1, RING2 and RING2 pins are restored to their default

settings.

4.3.4 Incoming Calls

Incoming voice calls and calls from analog lines are directed to the analog ports and all other incoming calls

are ignored.

MX-COM, Inc

4800 Bethania Station Road, Winston-Salem, NC, 27105-1201, USA

www.mxcom.com tel: 800 638 5577 336 744 5050 fax: 336 744 5054

All trademarks and service marks are held by their respective companies

2000 MX-COM, Inc.

Doc. # 20480214.001

2000 Chiron Technology Limited

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