Chapter 7 Configuring and Debugging Fax Services

Using Fax Pass-through Mode

Dial-Peer Level Commands

You can enable fax pass-through mode for communication between a Cisco IOS gateway and the specified Cisco ATA using the following dial-peer level commands:

Procedure

Step 1 Perform the command:

dial-peer voice tag voip

Step 2 Perform the command:

modem passthrough {NSE [payload-type number] codec {g711law g711alaw} [redundancy] system}

a.The default of this command is: modem passthrough system

When using the default configuration, the dial-peer fax pass-through configuration is defined by the voice service voip command. When the system option is used, no other parameters are available.

When the NSE is configured in the fax pass-through command at the dial-peer level, the fax pass-through definition in the dial-peercommand takes priority over the definition in the voice service voip command.

b.The payload-typenumber, codec, and redundancy parameters can also be used. For example, the command:

modem passthrough NSE codec g711law

means that the Cisco ATA will use the NSE payload-type number 100, G.711∝-law codec, and no redundancy in fax pass-through mode.

Step 3 When setting up dial-peer for fax pass-through, it is necessary to set up a pair of dial-peers for inbound and outbound calls between the Cisco ATA and Cisco IOS gateways. You do this by specifying the destination-patternand incoming-called number. The destination-patternshould point to the Cisco ATA, while the incoming-called number should apply to all numbers that the Cisco ATA is allowed to dial.

Disable Fax Relay Feature

Fax relay may be enabled by default for some IOS gateways. If you do not disable the fax relay feature, it may override the precedence of fax/modem pass-through and cause the fax transmission to fail. It is necessary to disable fax relay at the dial-peer or system level with the following command:

fax rate disable

Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator’s Guide (SIP)

 

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Cisco Systems 186, 188 manual Disable Fax Relay Feature, Perform the command