Specifications

23-7
Cisco Unity Express Voice-Mail and Auto-Attendant CLI Administrator Guide for 3.0 and Later Versions
OL-14010-09
Chapter 23 Configuring Your Cisco IOS Gateway for T.37 On-Ramp and Off-Ramp Fax Support
Configuration Options
Figure 23-4 High-Level Fax Call Flow
When the fax detect application is configured in connect first mode, it connects the call before listening
for the fax tones. The sequence of events, as shown in Figure 23-4, are:
• The fax call is initiated from the fax machine. The fax machine establishes a POTS connection to
the Cisco IOS fax gateway POTS dial peer using an FXS or FXO port. (This is shown in
Figure 23-4
as step 1.)
• The inbound POTS dial peer that is configured with the fax detection application creates a call leg
between an FXO or FXS port, a POTS dial peer, and a VoIP dial-peer. (This is shown in
Figure 23-4
as step 2.)
• The fax detection application establishes second leg of call between a VoIP/SIP dial peer and a
phone, or a VoIP/H.323 dial peer and a phone. When the phone starts ringing (corresponding to the
phone number in the single DID case), the user picks up the phone or call and is transferred to the
voice mail. After the call is established, the gateway starts listening for the CNG tones. If the
gateway is not able to establish that it is fax call within the equivalent of two CNG tones
(six
seconds), the call is treated as a voice mail call. (This is shown in Figure 23-4 as steps 3 and 5)
However, if the gateway detects that it is a fax call, the voice leg of call is disconnected and call is
transferred to a MMoIP dial peer. (This is shown in
Figure 23-4 as step 4.)
• If the call is a voice call and Cisco Unity Express is integrated with Cisco Unified
Communications
Manager, the voice call is established. (This is shown in Figure 23-4 as step 3.) If
there is no answer, the call is forwarded to Cisco Unity Express. (This is shown in Figure 23-4 as
step 6.)
• If the call is a voice call and Cisco Unity Express is integrated with Cisco Unified CME, the voice
call is established. (This is shown in
Figure 23-4 as step 5.) If there is no answer, the call is
forwarded to Cisco Unity Express (This is shown in Figure 23-4 as step 8.)
230492
1
2
43 5
76 8
Fax using
the fax machine
POST dial peer
VoIP or H.323 or
MMoIP dial peer
MMoIP
(convert to T.37 fax e-mail)
VoIP
Cisco Unified CallManager Express
H.323
Cisco Unified CallManager
Cisco Unity Express