Installation and Maintenance Manual
Avaya B179 SIP Conference Phone Installation and Administration Guide
27
SETTINGS
G711 Alaw G.711 is an ITU-T standard codec that uses audio companding.
Companding algorithms reduce the dynamic range of an audio
signal. In analog systems, this can increase the signal-to-noise
ratio achieved during transmission and, in the digital domain, can
reduce the quantization error.
Two main compression algorithms are dened in the standard,
the µ-law algorithm (used in North America and Japan) and A-law
algorithm (used in Europe and the rest of the world).
G711 Ulaw See G711 µ-law above.
G729 G.729 is an ITU-T standard codec that operates at 8 kbit/s. It is
mostly used in VoIP applications with low bandwidth requirement.
On phone: > SETTINGS > ADVANCED > (PIN) > MEDIA > CODEC (6,2,4,1).
Security
The media in VoIP calls is usually sent using the RTP protocol (Real-time Transport
Protocol). RTP is a standardized packet format for delivering audio and video over the
Internet.
SRTP (Secure Real-time Transport Protocol) is an extension of RTP to provide encryption,
message authentication and integrity for the audio and video streams.
All devices must support SRTP to establish a connection. It is therefore possible to set
SRTP as disabled, optional or mandatory.
RTCP can be used to control the RTP session. When using SRTP, the same security-
related features are added to the control protocol. SRTCP (Secure Real Time Control
Protocol) can be either encrypted or not encrypted.
SRTP If set to disabled, the media is sent using RTP. Note that despite
this setting, the Avaya B179 will still use a secure channel if the
opposite device demands it.
If set to optional or mandatory, a padlock will be shown in the
bottom right-hand corner of the screen. If the other devices sup-
port SRTP, the padlock will be locked. Otherwise, an open padlock
will be displayed.
If set to mandatory, the call will not be connected if the other
devices do not support SRTP.
SRTCP Is automatically used when SRTP is enabled. Can be set to use
encryptation or not.