Configuring Rerouting of Calls to Fax Destinations

You can configure the device to reroute incoming SBC calls identified as fax calls to a new IP destination. The device identifies a fax call if it detects, within a user-defined interval, a calling (CNG) tone on the originator side (incoming IP leg). If the device detects a fax call, it terminates the call and reroutes it using a new INVITE to the new fax destination (new IP Group). If the initial INVITE that was used to establish the voice call was already sent, the device sends a CANCEL (if not connected yet) or a BYE (if already connected) to release the call (with the internal disconnect reason RELEASE_BECAUSE_FAX_REROUTING, translated to Q.850 reason GWAPP_NORMAL_UNSPECIFIED 31).

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You must configure the originating fax to use the G.711 coder.

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If the remote side replies with T.38 or G.711 VBD, fax rerouting is not done.

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If both fax rerouting and fax re-INVITE are configured, only fax rerouting is done.

The following provides a basic example on how to configure fax rerouting.

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To configure fax rerouting:

Open the Fax/Modem/CID Settings page (Setup menu > Signaling & Media tab > Media folder > Fax/Modem/CID Settings).

In the 'Fax Detection Timeout' field [SBCFaxDetectionTimeout], enter the duration (in seconds) for which the device attempts to detect fax (CNG tone):

From the 'CNG Detector Mode' drop-down list [CNGDetectorMode], select Event Only.

Upload an ini file to the device through the Auxiliary Files page (see Uploading Auxiliary Files through Web Interface) with the following parameter setting, which enables in-band network detection related to fax:

EnableFaxModemInbandNetworkDetection = 1

In the IP Groups table (see Configuring IP Groups), configure the following IP Groups:

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IP Group #0 "HQ": This is the source IP Group, sending voice calls and fax calls.

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IP Group #1 "Voice": This is the destination for voice calls sent from IP Group #0.

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IP Group #2 "Fax": This is the destination for fax calls sent from IP Group #0.

For the fax destination (IP Group #2), do the following:

In the Coders Groups table (see Configuring Coder Groups), configure a Coder Group with T.38 to enable fax transmission over IP.

In the IP Profiles table (see Configuring IP Profiles), configure an IP Profile:

From the 'Fax Coders Group' drop-down list, select the Coder Group that you configured above.

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From the 'Fax Mode' drop-down list, select Handle always.

In the IP Groups table, edit IP Group #2, and then from the 'IP Profile' drop-down list, select the IP Profile that you configured above.

For the voice destination (IP Group #1), do the following:

In the IP Profiles table, configure an IP Profile - from the 'Fax Rerouting Mode' drop-down list, select Rerouting without delay:

In the IP Groups table, edit IP Group #1, and then from the 'IP Profile' drop-down list, select the IP Profile that you configured above.

In the IP-to-IP Routing table (see Configuring SBC IP-to-IP Routing Rules), configure the following adjacent rows of IP-to-IP Routing rules:

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IP-to-IP Routing Rule #0 to route voice calls from IP Group #0 to IP Group #1:

Match
Source IP Group	HQ (IP Group #0)
Call Trigger	Initial Only
ReRoute IP Group	Voice (IP Group #1)
Action
Destination Type	IP Group
Destination IP Group	Voice (IP Group #1)

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IP-to-IP Routing Rule #1 to route fax calls from IP Group #0 to IP Group #2:

Match
Source IP Group	HQ (IP Group #0)
Call Trigger	Fax Rerouting
Action
Destination Type	IP Group
Destination IP Group	Fax (IP Group #2)