ZTE Corporation ZXV10P802 Manuale Utente

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including G.711(a/µ) (also known as PCMU/PCMA), 
G.723.1, G.729A/B, G.726-32, iLBC, G.722 
(wide-band). 
 
Configure Vocoders in a preference list that is included 
with the same preference order in SDP message. 
Enter the first Vocoder in this list by choosing the 
appropriate option in “Choice 1”. Similarly, enter the 
last Vocoder in this list by choosing the appropriate 
option in “Choice 8”.   
SRTP Mode 
Enable SRTP mode based on selection. Default is 
“No”.  
Symmetric RTP 
Selects whether or not symmetric RTP is supported. 
Silence Suppression  This controls the silence suppression/VAD feature of 
the audio codec G.723 and G.729. If set to “Yes”, when 
silence is detected, a small quantity of VAD packets 
(instead of audio packets) will be sent during the period 
of no talking. If set to “No”, this feature is disabled. 
Voice Frames per 
TX 
This field contains the number of voice frames to be 
transmitted in a single Ethernet packet (be advised the 
IS limit is based on the maximum size of Ethernet 
packet is 1500 byte (or 120kbps)).   
 
When setting this value, be aware of the requested 
packet time (ptime, used in SDP message) is a result 
of configuring this parameter. This parameter is 
associated with the first codec in the above codec 
Preference List or the actual used payload type 
negotiated between the 2 conversation parties at run 
time. E.g., if the first codec is configured as G.723 and 
the “Voice Frames per TX” is set to 2, then the “ptime” 
value in the SDP message of an INVITE request will be 
60ms because each G.723 voice frame contains 30ms 
of audio. Similarly, if this field is set to 2 and the first 
codec is G.729 or G.711 or G.726, then the “ptime” 
value in the SDP message of an INVITE request will be 
20ms.