Expert Documentation

G.722 codec, without the need for any codec pass-through in direct RTP mode for SIP phones
and SIP Trunks (refer to Codec Pass-Through ).
The G.722 codec is supported on the following sets:
- 8082 My IC Phone
- 4135 IP Conference Phone
- SIP phones
Note 1:
G722.2 can also be supported with Open SIP Phone and Basic SIP Phone according to the type of set.
New values have been introduced in the ARS table for the Codec/Framing field:
- G722/G711_20: this value corresponds to the codec list: G722.2, G722, G711.a, G711.µ
with this priority order and with a framing of 20ms.
- G722/G711_30: this value corresponds to the codec list: G722.2, G722, G711.a, G711.µ
with this priority order and with a framing of 30ms.
- G722/G711_60: this value corresponds to the codec list: G722.2, G722, G711.a, G711.µ
with this priority order and with a framing of 60ms.
For these values, the codec to use is negotiated from actual capabilities. The G722 codec is
used in priority, G711 is a second choice, used when the G722 codec is not supported by the
remote Gateway, or when the call is initiated or sent to a non G722 compliant access (non SIP
access or SIP access that does not support G722) on the Alcatel-Lucent OmniPCX Office
Communication Server.
The SDP offers and responses sent by the Alcatel-Lucent OmniPCX Office Communication
Server are built according to the following algorithm:
- For SDP offers received from a SIP set or a SIP trunk (transit call)
• If the ARS rule is configured with “G722/G711_XX”, the codecs transmitted are the
codecs common to the two parties (if both G722 and G711 are transmitted, G722 is
placed before G711). The Ptime value negotiated is the one which is in the ARS table
(here replaced by “XX”)
• If the ARS table contains “Default”, the codecs transmitted are the codecs common to
the two parties in the order specified by the default list. The Ptime value is not forced.
- For SDP answers transmitted by the Alcatel-Lucent OmniPCX Office Communication
Server
• If the ARS rule is configured with “G722/G711_XX”
• If the offer received contains the G722 codec, the only codec transmitted in the
answer is G722.
• If the offer received contains the G711 codec and does not contain G722 codec,
the only codec transmitted in the answer is G711.
• If the offer received does not contain a G722 or G711 codec, the call is rejected.
• If the ARS table contains “Default”
• If the call is sent to a non SIP phone, the codec transmitted is the first common
codec between the codecs of the offer and those that are in the default table. If
there is no common codec, the call is rejected.
• If the call is sent to a SIP phone, the set transmits the selected codec and the
Alcatel-Lucent OmniPCX Office Communication Server selects the first codec in
the SDP answer of the SIP phone.
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