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Catalyst Blade Fax Relay Configuration

The 6608 is a blade for the Catalyst 6000/6500 series of switches. This card is MGCP controlled by Unified CM and features eight T1 or E1 ports, each of which is treated as a separate gateway. The 6608 supports Cisco fax relay only, not modem relay or text relay.

The 6608 is configured via the Unified CM graphical user interface (GUI). Figure 10-1 illustrates the default fax settings for a 6608 port. This particular screenshot is from Cisco Unified Call Manager (CUCM) Version 5.0(4), but all Unified CM versions from the past few years have these same options.

Figure 10-1 Cisco Fax Relay Configuration for a 6608 Gateway

By default, the 6608 is configured for Cisco fax relay because the Fax Relay Enable box is checked, as shown in Figure 10-1. This setting also disables passthrough as the transport mechanism for fax calls. Table 10-23 details the additional Cisco fax relay GUI options for the 6608 in the Fax and Modem Parameters section.

Table 10-23 Cisco Fax Relay Configuration Parameters for the 6608

Configuration
Parameter	Options	Function
Fax Relay Enable	Enable/Disable	When this box is checked, Cisco fax relay
		is enabled for the 6608. When this box is
		not checked, NSE-based passthrough is
		used to handle fax calls.
		Note: Cisco fax relay is enabled by
		default.
Fax Error Correction	Enable/Disable	When this box is checked, the 6608
Mode Override		automatically disables ECM for all Cisco
		fax relay calls.
		Note: By default, this box is checked, and
		ECM is disabled.
Maximum Fax Rate	2400	Sets the maximum speed at which faxes
	4800	can negotiate.
	7200	Note: The default setting is 14400 bps.
	9600
	12000
	14400
Fax Payload Size	20-48	Configures the number of payload bytes
		for each Cisco fax relay packet.
		Note: The default value is 20 bytes.
		Changing this value will alter the delay
		and bandwidth characteristics of the fax
		relay call.
Non Standard Facilities	0-65535	Overrides the country code portion of the
Country Code		T.30 NSF message to this configured
		value.
		Note: The default value is 65535.
Non Standard Facilities	0-65535	Overrides the vendor code portion of the
Vendor Code		T.30 NSF message to this configured
		value.
		Note: The default value is 65535.

The additional fax relay configuration parameters defined in Table 10-23 should look familiar because these same parameters are available in the IOS CLI. Although the 6608 and IOS gateways share the same behavior of having Cisco fax relay enabled by default, the maximum fax rate and ECM settings differ. The IOS gateways default to fax rate voice with ECM enabled, whereas the 6608 defaults to 14400 bps with ECM disabled. When integrating 6608 and IOS voice gateways, confirm that these settings are the same.

Another important field to pay attention to in the 6608 GUI configuration is Port Used for Fax Calls. If the box is not checked, Cisco fax relay will not function.

TIP The 6624 Catalyst blade contains 24 analog FXS ports. Like the 6608, this product is currently at an End of Life (EOL) status, but a large number of these cards are still being used. The configuration of the 6624 from a fax relay perspective should be the same as shown earlier for the 6608.

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