McDewey

Note: This command also activates the packet loss concealment feature. fax-relay ECM disable Command

<#root> vnt-3660-23(config-dial-peer)# dial-peer voice 3 vnt-3660-23(config-dial-peer)# fax-relay ECM disable

9. Enable T.38 Packet Redundancy (T.38 VoIP Only) If T.38 for VoIP is used as the fax relay protocol, the T.38 packet redundancy feature can be turned on if you configure this command under the appropriate dial peers on both gateways: T.38 Packet Redundancy

<#root> vnt-3660-23(config-dial-peer)# fax protocol t38

Ls-redundancy X Hs-redundancy Y

where X > 0 and Y = 0 (only make changes to Ls-redundancy) If Cisco proprietary fax relay is in use, an alternative or additional option to disable ECM is to change fax relay protocol to T.38 so that the T.38 packet redundancy feature can be tested. This feature can alleviate failure due to packet loss, but note that T.38 Packet Redundancy significantly increases bandwidth usage, and it is preferable to eliminate the packet loss where possible. 10. Set the fax NSF Command to All Zeroes The fax NSF command can be helpful for the brands of fax machines that alter the NSF field within fax negotiation for proprietary encodings. This command allows the router that does fax relay to override the settings made by the fax machines that attempts to implement proprietary encodings. Before the fax NSF command was available, fax relay would fail for these brands of fax machines. Typically the fax NSF command is used to set the NSF field to all zeroes, which forces a standard fax negotiation from both sides. This command has been successful with certain brands such as Harris and Lanier, and it is recommended when fax relay fails. fax NSF Command

<#root> vnt-3660-23(config-dial-peer)#