/mcp<#root> vnt-3660-23(config-dial-peer)# dial-peer voice 3 voip vnt-3660-23(config-dial-peer)# fax protocol ? cisco Use Cisco proprietary protocol system Use choice specified in global fax protocol CLI t38 Use T.38 protocol
The cisco option configures Cisco fax relay. The t38 option disables Cisco fax relay and enables T.38. Certain voice platforms such as the Cisco 5350 and 5400 support only T.38. For interoperability, T.38 must be explicitly configured on platforms where Cisco fax relay is the default. The system option allows the dial- peer to inherit the fax relay protocol that is configured globally with the voice service voip command. If nothing is configured under the voice service voip command, the default is Cisco fax relay. The default setting of the fax protocol command is the system option. Because the system option defaults to Cisco fax relay, VoIP dial-peers always default to Cisco fax relay when nothing is explicitly configured globally.
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! voice service voip !
!--- Note that there is no fax protocol configured so the !--- default is Cisco fax relay. Any dial-pee
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! dial-peer voice 3 voip destination-pattern 1000 session target ipv4:10.1.1.1 !
!--- Note that because fax protocol is not configured under !--- this VoIP dial-peer, the default is fa
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Troubleshooting These steps have been shown to resolve the majority of issues that involve fax relay over VoIP, VoATM, and VoFR. Information that is specific to a particular encapsulation type or fax relay type is noted.