Unicorn 3112 User Manual
Copyright © 2008
Hanlong Technology Co., Ltd
Page 27 of 42
FXS PORT SETTING
Setting Options
Meaning
Preferred Vocoder
(in listed order)
The Unicorn 3112 supports up to 7 different Vocoder types
including G.711 A-/U-law
，
G.723.1, G.726, G.728, G.729A/B,
iLBC(Pending). Depending on the product model, some of
these Vocoders may not be provided in standard release.
Users can configure Vocoders in a preference list that will be
included with the same preference order in SDP message. The
first Vocoder in this list can be entered by choosing the
appropriate option in “Choice 1”. Similarly, the last Vocoder in
this list can be entered by choosing the appropriate option in
“Choice 7”.
Voice Frames per
TX
This field contains the number of voice frames to be transmitted
in a single packet. When setting this value, the user should be
aware of the requested packet time (used in SDP message) as
a result of configuring this parameter. This parameter is
associated with the first vocoder in the above vocoder
Preference List or the actual used payload type negotiated
between the 2 conversation parties at run time. e.g., if the first
vocoder is configured as G723 and the “Voice Frames per TX”
is set to be 2, then the “ptime” value in the SDP message of an
INVITE request will be 60ms because each G723 voice frame
contains 30ms of audio. Similarly, if this field is set to be 2 and if
the first vocoder chosen is G729 or G711 or G726, then the
“ptime” value in the SDP message of an INVITE request will be
20ms. If the configured voice frames per TX exceeds the
