Signaling levels
MFC signaling uses pairs of frequencies to represent digits, and is divided into two levels:
• Level 1: used when a call is first established and may be used to send the dialed digits.
• Level 2: used after Level 1 signaling is completed and may contain such information as
the status, capabilities, or classifications of both calling parties.
Forward and backward signals
When one NT5K21 XMFC/MFE card sends a pair of frequencies to a receiving XMFC/MFE
card (forward signaling), the receiving XMFC/MFE card must respond by sending a different
set of frequencies back to the originating XMFC/MFE card (backward signaling). In other
words, the receiving card is always "compelled" to respond to the originating card.
In summary, the signaling works as follows:
• The first XMFC/MFE card sends a forward signal to the second card.
• The second card hears the forward signal and replies with a backward signal.
• The first card hears the backward signal and "turns off" its forward signal.
• The second card hears the forward signal being removed and removes its backward
signal.
• The first XMFC/MFE can either send a second signal or drop out of the call.
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.
Table 135: MFC Frequency values
on page 296 lists the frequency values used for forward
and backward signals.
Table 135: MFC Frequency values
Digit
Forward direction DOD-Tx, DID-
Rx
backward direction DOD-Rx, DID-
Tx
1
1380 Hz + 1500 Hz
1140 Hz + 1020 Hz
2
1380 Hz + 1620 Hz
1140 Hz + 900 Hz
NT5K21 XMFC/MFE card
296 Circuit Card Reference
July 2011
Summary of Contents for 1000 Series
Page 1: ...Circuit Card Reference Nortel Communication Server 1000 7 0 NN43001 311 04 04 July 2011 ...
Page 20: ...20 Circuit Card Reference July 2011 ...
Page 30: ...Introduction 30 Circuit Card Reference July 2011 Comments infodev avaya com ...
Page 116: ...Option settings 116 Circuit Card Reference July 2011 Comments infodev avaya com ...
Page 143: ...Figure 25 CP PIV card front Physical description Circuit Card Reference July 2011 143 ...
Page 148: ...NT4N39AA CP Pentium IV Card 148 Circuit Card Reference July 2011 Comments infodev avaya com ...
Page 287: ...Figure 86 Clock Controller Option 3 Operation Circuit Card Reference July 2011 287 ...
Page 302: ...NT5K21 XMFC MFE card 302 Circuit Card Reference July 2011 Comments infodev avaya com ...
Page 346: ...NT6D80 MSDL card 346 Circuit Card Reference July 2011 Comments infodev avaya com ...
Page 353: ...Figure 96 NTDK16 DLC Functional description Circuit Card Reference July 2011 353 ...
Page 461: ...Figure 147 Paging trunk operation Applications Circuit Card Reference July 2011 461 ...
Page 462: ...NT8D15 E and M Trunk card 462 Circuit Card Reference July 2011 Comments infodev avaya com ...
Page 500: ...NTAK09 1 5 Mb DTI PRI card 500 Circuit Card Reference July 2011 Comments infodev avaya com ...
Page 512: ...NTAK10 2 0 Mb DTI card 512 Circuit Card Reference July 2011 Comments infodev avaya com ...
Page 534: ...NTAK79 2 0 Mb PRI card 534 Circuit Card Reference July 2011 Comments infodev avaya com ...
Page 550: ...NTBK22 MISP card 550 Circuit Card Reference July 2011 Comments infodev avaya com ...
Page 560: ...NTBK50 2 0 Mb PRI card 560 Circuit Card Reference July 2011 Comments infodev avaya com ...
Page 595: ...Figure 165 MGC block diagram Introduction Circuit Card Reference July 2011 595 ...
Page 662: ...NTRB21 DTI PRI DCH TMDI card 662 Circuit Card Reference July 2011 Comments infodev avaya com ...
Page 668: ...NTVQ01xx Media Card 668 Circuit Card Reference July 2011 Comments infodev avaya com ...
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