Calling Line Identifier
MX602 - PRELIMINARY INFORMATION
16
5.2.3 Detailed Procedure for CIDCW Transaction Initiation Detection
1. INITIAL state
The MX602 is in the Tone Alert Detect mode. On the rising edge of the DET line, start the timer, and transition to the
WAIT_T1 state.
2. WAIT_T1 state
During this state, the DET output high time is measured so that pulses lasting less than T1 may be ignored.
WHILE Timer < T1
IF DET goes low
Reset the timer.
Transition to the INITIAL state.
Initiate local speech muting.
Transition to MEAS_DET_HIGH state.
3. MEAS_DET_HIGH state
WHILE Timer < 65ms
IF DET goes low
IF Timer < T3
Unmute local speech.
Reset the timer.
Transition to the INITIAL state.
ELSE
Set MX602 to FSK Receive Mode.
Reset the timer.
Transition to the CONFIRM_QUIET state.
Unmute local speech.
Transition to the WAIT_DET_LOW state.
4. CONFIRM_QUIET state
WHILE Timer < 50ms
IF DET goes high
Set MX602 to Tone Alert Detect Mode.
Unmute local speech.
Reset the timer.
Transition to the INITIAL state.
Transition to the COMPLETE_CIDCW state.
5. COMPLETE_CIDCW state
This state handles the remaining CIDCW transaction functions e.g. determine that no near end extensions are off hook,
emit a CPE ACK to Central Office via a DTMF D tone signal, receive the FSK Caller ID data stream, etc.
WHEN CIDCW transaction is complete
Set the MX602 to Tone Alert Detect Mode.
Unmute local speech.
Reset the timer.
Transition to the INITIAL state.
6. WAIT_DET_LOW state
WHEN DET goes low
Reset the timer
Transition to the INITIAL state.
Times T1, T2, & T3
The values given below have been selected to give an extremely low incidence of false CAS detections while maintaining
a high probability of decoding correct CIDCW initiation signals by taking advantage of the specific profile of MX602's
responses to typical speech and CAS signals. Two timing options are given, Telephone Set and Adjunct Box, the choice
being determined principally by how easily local speech can be muted. The Adjunct Box option reduces the frequency of
short speech mutes by a factor of about 5 at the expense of a small increase in the number of missed CAS signals when
compared to the Telephone Set option.
© 1998 MX•COM Inc.
www.mxcom.com Tele: 800 638-5577 336 744-5050 Fax: 336 744-5054
Doc. # 20480136.004
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
All trademarks and service marks are held by their respective companies.
CMLMICRO [ CML MICROCIRCUITS ]
