Specifications

23-8
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
• If the call is a fax call, irrespective of how Cisco Unity Express is integrated, the fax application
configured on the outbound MMoIP dial peer converts the fax into an e-mail message with TIFF
attachment(s) and sends the message over SMTP to Cisco Unity Express (This is shown in
Figure 23-4 as step 7.)
From the user’s point of view, this is the sequence of events:
1. The fax call is initiated.
2. The called number starts ringing.
3. The user picks up the phone or the call is transferred to the voice mail.
4. If the user picks up the phone, they hear CNG tones (in the case of fax calls) or voice (in the case of
voice calls). At this point:
– If the user disconnects the call before the fax gateway can detect that it is a fax call, the call is
disconnected and fax must be resent.
– If the user puts the call on hold for the six seconds that the gateway requires to detect that it is
a fax call, the call leg between gateway and Cisco Unified CME or Cisco
Unified
Communications Manager is disconnected. The call is established to a MMoIP dial peer.
– If the user attempts to transfer the call to the fax number (MMoIP), the call transfer fails and
subsequently the call is disconnected.
5. If the call is forwarded to the voice mail of the user, the voice mail prompt starts playing. If the call
is a voice call, the user can leave a voice message. If the call is a fax, the CAG tone is detected within
six seconds, the voice call is pulled back, and another call leg to MMoIP dial-peer is established.
The voice leg of call is disconnected.
Using Connect First Mode with Separate DIDs
The sequence of events for the Connect First Mode with separate DIDs are similar to the sequence
described in the “Using Connect First Mode with Single DID” section on page 6. However, there is no
need for fax detection on the fax gateway because the fax has separate DID. Calls to the fax numbers are
routed by the fax gateway, and the MMoIP dial-peer is used to send the faxes to Cisco Unity Express
over SMTP in the form of e-mail messages (as described in the “Using the Fax Detection Application vs
the On-ramp Application” section on page 9). The calls to the voice numbers are routed to the VoIP dial
peer, using SIP for Cisco Unified CME and H.323 for Cisco Unified Communications Manager.
A single DID can exist along with separate DIDs. We recommend that you do not use the fax detection
application when there are separate DIDs for fax and voice calls in order to give the users a better
experience.
Using Listen First Mode with Single DID
When the fax detect application is configured in listen first mode, the fax detect application listens for
the CNG tones first and connects the call either to VoIP or MMoIP dial-peer based on whether the call
is a voice or fax call. The sequence of events, as shown in Figure 23-4, are:
1. The fax call is initiated from the fax machine. The fax machine establishes a POTS connection to
POTS dial peer using an FXS or FXO port. The fax detection application on the POTS dial-peer
listens for the fax tones. The fax application routes the call to either the MMoIP dial peer or
VoIP/H.323 dial peer. When fax gateway is listening for the fax tones, it can play some prompts to
the call originator. These prompts can be dial-tones, which simulate the tones that indicate that the
destination device is ringing. (This is shown in
Figure 23-4 as step 1.)