Other Features - Linksys SPA921-NA Administrator's Manual

Feature Descriptions

Other Features

Table 1-4
Table 1-4
Feature
Music On Hold
Secure Calls
Adjustable Audio
Frames Per Packet
DTMF
Call Progress Tone
Generation
Call Progress Tone
Pass Through
Jitter
Buffer—Dynamic
(Adaptive)
Linksys 900 Series IP Phone Administrator Guide
1-8
summarizes the features provided by SPA900 Series IP Phones.
Linksys ATA Features
Description
On a connected call, SPA900 Series IP phones may place the remote
party on call. If the remote party indicates that they can still receive
audio while the call is holding, the MOH server sends streaming
audio.
A user (if enabled by service provider or administrator) has the option
to make an outbound call secure in the sense that the audio packets in
both directions are encrypted.
This feature allows the user to set the number of audio frames
contained in one RTP packet. Packets can be adjusted to contain from
1–10 audio frames. Increasing the number of packets decreases the
bandwidth utilized, but it also increases delay and may affect voice
quality.
In-Band and Out-of-Band (RFC 2833) (SIP INFO *) SPA900 Series
IP phones may relay DTMF digits as out-of-band events to preserve
the fidelity of the digits. This can enhance the reliability of DTMF
transmission required by many IVR applications such as dial-up
banking and airline information.
SPA900 Series IP phones have configurable call progress tones.
Parameters for each type of tone may include number of frequency
components, frequency and amplitude of each component, and
cadence information.
This feature allows the user to hear the call progress tones (such as
ringing) that are generated from the far-end network.
SPA900 Series IP phones can buffer incoming voice packets to
minimize out-of-order packet arrival. This process is known as jitter
buffering. The jitter buffer size proactively adjusts or adapts in size,
depending on changing network conditions.
SPA900 Series IP phones have a Network Jitter Level control setting
for each line of service. The jitter level decides how aggressively
SPA900 Series IP phones try 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.
Chapter 1 Introducing Linksys 900 Series IP Phones
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