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7.2.12. Jitter Buffer – Dynamic (Adaptive)
The SPA can buffer incoming voice packets to minimize out-of-order packet arrival. This process is
known as jitter buffering. The Jitter Buffer size will proactively adjust or adapt in size depending on
changing network conditions.
The SPA has a Network Jitter Level control setting for each line of service. The jitter level decides
how aggressively the SPA will 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.
7.2.13. Full Duplex Audio
Full-duplex is the ability to communicate in two directions simultaneously so that more than one
person can speak at a time. Half-duplex means that only one person can talk at a time – like a CB
radio or walkie-talkie, which is unnatural in normal free-flowing two-way communications. The SPA
supports full-duplex audio.
7.2.14. Echo Cancellation – Up to 8 ms Echo Tail
The SPA supports hybrid line echo cancellation. This feature uses the G.165 echo canceller to
eliminate up to 8 ms of line echo. This feature does not provide acoustic echo cancellation on
endpoint devices – that is, an end user’s speakerphone.
7.2.15. Voice Activity Detection with Silence Suppression & Comfort Noise Generation
Voice Activity Detection (VAD) and Silence Suppression is a means of increasing the number of calls
supported by the network by reducing the required bi-directional bandwidth for a single call. VAD
uses a very sophisticated algorithm to distinguish between speech and non-speech signals. Based
upon the current and past statistics, the VAD algorithm decides whether or not speech is present. If
the VAD algorithm decides speech is not present, the silence suppression and comfort noise
generation is activated. This is accomplished by removing and not transmitting the natural silence that
occurs in normal 2-way connection – the IP bandwidth is used only when someone is speaking.
During the silent periods of a telephone call additional bandwidth is available for other voice calls or
data traffic since the silence packets are not being transmitted across the network. Comfort Noise
Generation provides artificially generated background white noise (sounds), designed to reassure
callers that their calls are still connected during silent periods. If Comfort Noise Generation is not
used, the caller may think the call has been disconnected because of the “dead silence” periods
created by the VAD and Silence Suppression feature.
7.2.16. Attenuation / Gain Adjustment
7.2.17. Signaling Hook Flash Event
The SPA can signal hook flash events to the remote party on a connected call. This feature can be
used to provide advanced mid-call services with third-party-call-control. Depending on the features
that the service provider will offer using third-party-call-control, the following three SPA features may
be disabled to correctly signal a hook-flash event to the softswitch:
1. Call Waiting Serv
2. Three Way Call Serv
3. Three Way Conf Serv
7.2.18. Configurable Flash / Switch Hook Timer
7.2.19. Configurable Dial Plan with Interdigit Timers
The SPA has three configurable interdigit timers:
•
Initial timeout (T) = handset off hook, no digit pressed yet.
