Chapter. - Cisco ATA 191 Administration Manual

Other ATA Voice Quality Features
• Modem pass-through mode can be triggered by predialing the Vertical Service Activation Code for the
Modem Line Toggle Code. You can configure this setting in the Vertical Service Activation Codes
section of the Regional page.
• A CED/CNG tone or an NSE event triggers FAX pass-through mode.
• Echo canceller is automatically disabled for Modem passthrough mode.
• Echo canceller is disabled for FAX pass-through if FAX Disable ECAN (Line 1 or 2 tab) is set to "Yes"
for that line. In this case, FAX pass-through is the same as Modem pass-through.
• Call waiting and silence suppression are automatically disabled for both FAX and Modem pass-through.
Out-of-band DTMF transmission is disabled during modem or fax passthrough.
Adaptive Jitter Buffer
The ATA can buffer incoming voice packets to minimize the impact of variable network delays. This process
is known as jitter buffering. The size of the jitter buffer adjusts to changing network conditions. The ATA
has a Network Jitter Level control setting for each line of service. The jitter level determines how aggressively
the ATA tries to shrink the jitter buffer over time to achieve a lower overall delay. If the jitter level is higher,
it shrinks more gradually. If jitter level is lower, it shrinks more quickly. You can use the default settings or
configure this feature in the Network Settings section of the "Voice Settings Configuration" chapter.
Adjustable Audio Frames Per Packet
This feature allows you to set the number of audio frames contained in one RTP packet. Packets can be adjusted
to contain from 1 to 10 audio frames. Increasing the number of packets decreases the bandwidth utilized, but
it also increases delay and may affect voice quality. You can configure this setting in the RTP Parameters
section of the SIP page.
DTMF Relay
The ATA may relay DTMF digits as out-of-band events to preserve the fidelity of the digits. This action
enhances the reliability of DTMF transmission required by many IVR applications such as dial-up banking
and airline information. You can configure this setting in the RTP Parameters section of the SIP page.
Call Progress Tones
The ATA has configurable call progress tones. Call progress tones are generated locally on the ATA and alert
you to a call's status. Parameters for each type of tone, such as a dial tone, may include frequency and amplitude
of each component, and cadence information. You can keep the default settings or configure these tones in
the Call Progress Tones section of the Regional page.
Call Progress Tone Pass Through
This feature allows you to hear the call progress tones (such as ringing) that are generated from the far-end
network.
Echo Cancellation
Impedance mismatch between the phone and the IP Telephony gateway phone port can lead to near-end echo.
The ATA has a near-end echo canceller that compensates for impedance mismatch. The ATA also implements
an echo suppressor with Comfort Noise Generator (CNG) so that any residual echo is not noticeable. This
feature is enabled by default. You can configure this setting in the Audio Configuration of the Line 1 and
Line 2 Settings (PHONE 1 and PHONE 2) page.
Cisco ATA 191 and ATA 192 Analog Telephone Adapter Administration Guide for Multiplatform Firmware
8
Get Started