R E V I E W D R A F T # 1 — C I S C O C O N F I D E N T I A L
3-9
Cisco WRP500 Administration Guide
Chapter 3 Configure Voice Services
Optimize Fax Completion Rates
Note
Only T.38 Fax is supported. The WRP500 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:
•
Call Waiting Serv
: no
•
Three Way Call Serv
: 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 WRP500 by configuring the following parameter on the Line tab for the FXS port
to which the FAX machine is connected:
FAX
_Enable T38:
Yes
Note
If a T.38 call cannot be set-up, then the call automatically reverts to G.711 fallback.
Step 5
If you are using a Cisco media gateway use the following settings:
Make sure the Cisco gateway is correctly configured for T.38 with the SPA dial peer. For example:
fax protocol T38
fax rate voice
fax-relay ecm disable
fax nsf 000000
no vad
Fax Troubleshooting
If you have problems sending or receiving faxes, complete the following steps:
Step 1
Verify that your fax machine is set to a speed between 7200 and 14400.
Step 2
Send a test fax in a controlled environment between two ATAs.
Step 3
Determine the success rate.
