DRAFT
© 2003 - 2005 Sipura Technology, Inc
Proprietary (See Copyright Notice on Page 2)
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G.729A
The ITU G.729 voice coding algorithm is used to compress digitized speech. Sipura supports G.729.
G.729A is a reduced complexity version of G.729. It requires about half the processing power to code
G.729. The G.729 and G.729A bit streams are compatible and interoperable, but not identical.
G.723.1
The SPA supports the use of ITU G.723.1 audio codec at 6.4 kbps.
Codec Selection
The administrator can select which low-bit-rate codec to be used for each line. G711a and G711u are
always enabled.
Dynamic Payload
When no static payload value is assigned per RFC 1890, the SPA can support dynamic payloads for
G.726.
Adjustable Audio Frames Per Packet
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.
DTMF: In-band & Out-of-Band (RFC 2833) (SIP INFO *)
The SPA 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.
Call Progress Tone Generation
The SPA has 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.
Call Progress Tone Pass Through
This feature allows the user to hear the call progress tones (such as ringing) that are generated from the
far-end network.
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.
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