Nortel DMS-100 Series Maintenance Manual page 30

1-14 Maintenance overview
Example of a DSCWID call on a 2500 set
CC
When a UTR channel is not available, the system continues to send alerting
signals to the CPE. If all UTR channels are not available, the system does
not send data to the CPE. In the proprietary DSCWID, when the SMS
cannot attach a UTR, the SMS ignores a flash. For Bellcore compliance, the
switch must provide options if the SMS detects a flash and the switch cannot
attach a UTR. For compliance, the SMS sends a flash to the CC if the SMS
cannot attach a UTR in 400 ms. If the CC does not acknowledge the
notification of a pending call in 10 s, the system sends a second signal. If
the CPE does not receive display data because UTR channels are not
available, the system holds the data. If alerting occurs again, the system
sends the data again.
After the SMS receives a flash signal from a customer ADSI compatible
CPE, the SMS starts a T-tone timer. The T-tone timer times for the
maximum time allowed between a flash and the DTMF on an ADSI set.
The timeout is 600 ms. During the timeout, the speech path is muted. The
SMS starts the T-tone timer for the first option selection during a DSCWID
call. The CPE type does not affect this process. Any ADSI DSCWID option
selections that follow also initiate the T-tone timer.
297-8231-550 Standard 09.01 August 1998
Data
SMS
SAS
CAS
DTMF digit
Flash to answer
Flash
Select option
DTMF digit
CPE