Configuring Voice Services
Optimizing Fax Completion Rates
Cisco Small Business WRP400 Administration Guide
39
3
Optimizing Fax Completion Rates
Issues can occur with fax transmissions over IP networks, even with the T.38
standard, which is supported by the WRP400. You can adjust several settings on
your WRP400 to optimize your fax completion rates.
NOTE
Only T.38 Fax is supported. The WRP400 supports one connection.
STEP 1
Ensure that you have enough bandwidth for the uplink and the downlink.
•
For G.711 fallback, it is recommend to have approximately 100Kbps.
•
For T.38, allocate at least 50 kbps.
STEP 2
To optimize G.711 fallback fax completion rates, set the following on the Line tab
of your ATA device:
•
Network Jitter Buffer
: very high
•
Jitter buffer adjustment
: disable
•
Call Waiting
: no
•
3 Way Calling
: no
•
Echo Canceller
: no
•
Silence suppression
: no
•
Preferred Codec
: G.711
•
Use pref. codec only
: yes
STEP 3
If you are using a Cisco media gateway for PSTN termination, disable T.38 (fax relay)
and enable fax using modem passthrough.
For example:
modem passthrough nse payload-type 110 codec g711ulaw
fax rate disable
fax protocol pass-through g711ulaw
STEP 4
Enable T.38 fax on the WRP400 by configuring the following parameter on the Line
tab for the FXS port to which the FAX machine is connected:
FAX_Passthru_Method: ReINVITE
