Grandstream Networks GXV3275 Administration Manual page 61

H.264 Payload Type
SRTP Mode
SRTP Key Length
Enable SRTP Key Life Time
Silence Suppression
Firmware Version 1.0.3.46

Standard: use AS format in session level; use TIAS format in
media level

Media Level: use AS format in media level

Session Level: use AS format in session level

No: no modifications in the session format
The default setting is "Media Level".
Note:
Please do not modify this setting without knowing the session format
supported by the server. Otherwise, it might cause video decoding
failure.
It is used to configure the H.264 codec message payload type format.
The default setting is 99. The valid range is from 96 to 127.
It is used to set if the phone system will enable the SRTP (Secured
RTP) mode. It can be selected from dropdown list:

Disable

Enabled but not forced

Enabled and forced
SRTP uses encryption and authentication to minimize the risk of denial
of service. (DoS). If the server allows to use both RTP and SRTP, it
should be configured as "Enabled but not forced". The default setting
is "Disable".
It is to configure all the AES (Advanced Encryption Standard) key size
within SRTP. It can be selected from dropdown list:

AES128&256 bit

AES 128 bit

AES 256 bit
If it is set to "AES 128&256 bit", the phone system will provide both
AES 128 and 256 cipher suite for SRTP. If set to "AES 128 bit", it only
provides 128 bit cipher suite; if set to "AES 256 bit", it only provides
256 bit cipher suite. The default setting is "AES128&256 bit".
It is used to configure whether to define SRTP key life time. When this
option is set to be enabled, during the SRTP call, the SRTP key will be
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valid within 2 SIP packets, and phone will renew the SRTP key after
this limitation. The default setting is "Yes".
It is used to set the silence suppression/VAD feature. If it is set to "Yes",
when silence is detected, a small quantity of VAD packets (instead of
GXV3275 Administration Guide Page 59 of 117