Advanced Options for Phone Services
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Optimize Fax Completion Rates
Issues can occur with fax transmissions over IP networks, even with the T.38 standard. Use the following
task to help avoid any issues.
Procedure
Step 1
Ensure that you have enough bandwidth for the uplink and the downlink.
• For G.711 fallback, we recommend approximately 100 kbps.
• For T.38, allocate at least 50 kbps.
Step 2
Click Voice in the menu bar, and then click Line 1 or Line 2 in the navigation tree.
Step 3
In the Network Settings section, enter the following settings:
• Network Jitter Level—very high.
• Jitter Buffer Adjustment—no.
Step 4
In the Supplementary Service Subscription section, enter the following settings:
• Call Waiting Serv—no.
• Three Way Call Serv—no.
Step 5
In the Audio Configuration section, enter the following settings to support T.38 fax:
• Preferred Codec—G.711u (USA) or G.711a (rest of the world).
• Use pref. codec only—Yes.
• Silence Supp Enable—No.
Optimize Fax Completion Rates, page 125
Dial Plan Configuration, page 127
Cisco ATA 191 and ATA 192 Analog Telephone Adapter Administration Guide for Multiplatform Firmware
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C H A P T E R
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