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G.729 – this codec uses the CS-ACELP (Conjugate-Structure Algebraic-Code-
Excited Linear-Prediction) algorithm with the resultant transmission rate of 8
kbps. The speech signal is split into blocks of 10 ms each. The parameters of
these blocks are then inserted in frames of the size of 10 bytes. 2-byte frames
are generated for noise transmission.
During call set-up, a codec is selected automatically for voice transmission. 2N BRI
®
gateway supports the codecs included in the table above. The type of codec to be
used depends on your VoIP network (individual devices) and your gateway 2N BRI
®
configuration. gateway is designed primarily for VoIP corporate networks and 2N BRI
®
tries to meet the opponent's codec requirements. If a codec is requested that is
incompatible with , the call will be rejected. 2N BRI Enterprise
®
The SIP and ITU-T H.323 recommended protocols are mostly used for connection
establishing, maintaining and cancelling. gateway uses the (Session 2N BRI
®
SIP
Initiation Protocol) signalling.
Tip
In the case of separated direct connection of your SIP Proxy and 2N
®
, use the G.711 codec to achieve a high voice quality. VoiceBlue Next
SIP Components
The following components are involved in the SIP message exchange:
UAC (User Agent Client) – the terminal device client, which initiates SIP
signalling.
UAS (User Agent Server) – the terminal device server, which responds to SIP
signalling from the UAC.
UA (User Agent) – a SIP network terminal (SIP phones, gateways to other
networks, etc.), which contains the UAC and UAS.
Proxy server – receives connection requests from the UA and transfers them to
the next Proxy server if the given station is not under it administration.
Redirect server – receives connection requests, but, instead of sending them to
the called line, sends them back to the requesting device asking for where to
route the request.
Location server – receives registration requests from the UA and updates the
terminal database accordingly.