ZyXEL Communications U-336E, User Manual

Page: 52 / 137

40 Special Functions
Extended Distinctive Ring (EDR)
Extended Distinctive Ring (EDR) is a special feature designed for
single telephone line home use to receive fax or data calls without
interfering with regular voice calls. When most users install a
fax/modem at home, they won’t subscribe to an extra telephone line
for occasional fax or data calls; however, fax/data calls do come in
from time to time.
If a user lets the fax/data software application answer, voice calls
will be missed. On the other hand, if the user or an answering
machine answers, fax or data calls may either be missed or the
person who answers the call has to go through some procedure to
get this call connected to the proper application. Either way is not
desirable.
Once enabled with the proper settings, EDR can:
1. Detect the data/fax CNG tone without physically answering the
call. After a CNG tone is detected, the modem will report
RING or RING n to the application software. The software can
cause the modem to answer the call.
2. Detect several DTMF tones without physically answering the
call. The DTMF tones, once detected by the modem, will be
reported as RING or RING n to the software application.
With these two functions, your modem can be installed with an
answering machine or voice telephone set at home. In most cases,
the modem should not be set to answer regular rings, nor to report
them. Thus, the software will not instruct the modem to answer the
call when the phone rings. When a call comes in, the answering
machine will answer the phone and play a voice message. At this
moment, the modem, having detected the ring signal is gone, will
start to listen to the line for CNG tone or DTMF tones.
If the remote caller is an unattended fax machine, it will send a
CNG tone for a period of time. The modem will detect the CNG