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7.2.4.1. G.711 (A-law and mµ-law)
This very low complexity codec supports uncompressed 64 kbps digitized voice transmission at one
through ten 5 ms voice frames per packet. This codec provides the highest voice quality and uses the
most bandwidth of any of the available codecs.
7.2.4.2. G.726
This low complexity codec supports compressed 16, 24, 32 and 40 kbps digitized voice transmission
at one through ten 10 ms voice frames per packet. This codec provides the high voice quality.
7.2.4.3. 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.
7.2.4.4. G.723.1
The SPA supports the use of ITU G.723.1 audio codec at 6.4 kbps. Up to 2 channels of G.723.1 can
be used simultaneously. For example, Line 1 and Line 2 can be using G.723.1 simultaneously, or
Line 1 or Line 2 can initiate a 3-way conference with both call legs using G.723.1.
7.2.5. Codec
Selection
The administrator can select which low-bit-rate codec to be used for each line. G711a and G711u
are always enabled.
7.2.6. Dynamic
Payload
When no static payload value is assigned per RFC 1890, the SPA can support dynamic payloads for
G.726.
7.2.7.
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.
7.2.8.
Modem and Fax Pass-Through
Modem Pass-through Mode can only be triggered by predialing the <Modem Line Toggle Code>.
FAX Pass-through Mode is triggered by CED/CNG tone or NSE events. Echo canceller is
automatically disabled for Modem Pass-through Mode only. Echo canceller is automatically disabled
only if <FAX Disable ECAN> (Line 1/2) is set to "yes" for that line (in that case FAX pass-through is
the same as Modem pass-through). Call-waiting and silence suppression is automatically disabled for
both FAX and Modem pass-through as before. In addition, out-of-band DTMF Tx is disabled during
modem or fax pass-through
.
7.2.9.
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.
7.2.10. 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.
7.2.11. 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.
