NT5K21XMFC/MFE card Page401 of 544
Option11C and 11C Mini TechnicalReference Guide
MFC signaling involves two or more levels of forward signals and two or
more levels of backward signals. Separate sets of frequencies are used for
forward and backward signals:
•Forward signals. Level I forward signals are dialed address digits that
identify the called party. Subsequent levels of forward signals describe
the category (Class of Service) of the calling party, and may include the
calling party status and identity.
•Backward signals. Level I backward signals (designated “A”) respond
to Level I forward signals. Subsequent levels of backward signals (B, C,
and so on) describe the status of the called party.
Table123 on page 401 lists the frequency values used for forward and
backward signals.
Table 1 23
MFC Frequency values (Part1 of 2)
Digit Forward direction
DOD-Tx, DID-Rx
backward direction
DOD-Rx, DID-Tx
11380 Hz + 1500 Hz 1140 Hz + 1020 Hz
21380 Hz + 1620 Hz 1140 Hz + 900 Hz
31500 Hz + 1620 Hz 1020 Hz + 900 Hz
41380 Hz + 1740 Hz 1140 Hz + 780 Hz
51500 Hz + 1740 Hz 1020 Hz + 780 Hz
61620 Hz + 1740 Hz 900 Hz + 780 Hz
71380 Hz + 1860 Hz 1140 Hz + 660 Hz
81500 Hz + 1860 Hz 1020 Hz + 660 Hz
91620 Hz + 1860 Hz 900 Hz + 660 Hz
10 1740 Hz + 1860 Hz 780 Hz + 660 Hz
11 1380 Hz + 1980 Hz 1140 Hz + 540 Hz
12 1500 Hz + 1980 Hz 1020 Hz + 540 Hz