McDewey

Troubleshoot Fax Relay Contents Introduction Prerequisites Requirements Components Used Overview of Fax and Fax Relay Fax Basics Fax Relay Basics Configuration Considerations fax rate Command fax-relay ECM disable Command fax NSF Command fax protocol Command Troubleshooting

1. Identify and Isolate the Problem
2. Check Basic Connectivity
3. Check for SLIPs and Other Errors on Digital Interfaces
4. Check Fax Interface-type
5. Make Sure that the Fax Codec is Loaded During the Fax Call
6. Disable Fax Relay and Change Codec for Passthrough
7. Check for Packet Loss on the VoX Network
8. Disable Fax Relay ECM (Cisco Proprietary VoIP Only)
9. Enable T.38 Packet Redundancy (T.38 VoIP Only)
10. Set the fax NSF Command to All Zeroes
11. Check if the MGCP Gateway is Configured for the FXR Package
12. Final Stages of Resolution Debugging T.30 Messages Fax Relay Debug Commands debug fax relay t30 all Debug vtsp all Debug vtsp vofr subframe 3 Additional Debug Commands Fax Analyzers Open a TAC Case Related Information Introduction This document describes basic troubleshooting and resolution to Cisco fax relay-related issues.