Cisco Small Business Voice Gateways and ATAs

In order to improve fax completion rates on the SPA2100, make sure:

• The SPA2100's firmware is the current version
• You have enough bandwidth for uplink and downlink. For G.711 fallback, ~100Kbps is recommended. For T.38, allocate at least 50Kbps.

In addition, configure these parameters:

• Set Network Jitter Buffer to Very High
• Set Jitter Buffer Adjustment to Disable
• Set Call Waiting to No
• Set 3-Way Calling to No
• Set Echo Canceller to No
• Set Silence Suppression to No
• Set Preferred Codec to G.711
• Set Use Preferred Codec Only to Yes

Note: For T.38 fax support, enable the feature by setting Fax Passthru Method to ReINVITE under the Line tabs. Note that if a T.38 call cannot be set up, then the call should automatically revert to G711 fallback.

If you are using a Cisco media gateway, make sure it is configured with T.38 for the SPA2100 corresponding dial peer. The dial peer should include:

• Fax Protocol should be set to T.38
• Fax Rate should be set to Voice
• Fax-Relay ECM should be set to Disable
• Fax NSF should be set to 000000
• No VAD