AudioCodes Mediant 500L User Manual page 440

Parameter
[IpProfile_ProfileName]
Media Security
SBC Media Security Mode
sbc-media-security-
behaviour
[IpProfile_SBCMediaSecurit
yBehaviour]
Gateway Media Security
Mode
media-security-behaviour
[IpProfile_MediaSecurityBeh
aviour]
User's Manual
The valid value is a string of up to 40 characters.
Defines the handling of RTP and SRTP for the SIP entity associated
with the IP Profile.

[0] As is = (Default) No special handling for RTP\SRTP is done.

[1] SRTP = SBC legs negotiate only SRTP media lines, and RTP
media lines are removed from the incoming SDP offer-answer.

[2] RTP = SBC legs negotiate only RTP media lines, and SRTP
media lines are removed from the incoming offer-answer.

[3] Both = Each offer-answer is extended (if not already) to two
media lines - one RTP and the other SRTP.
If two SBC legs (after offer-answer negotiation) use different security
types (i.e., one RTP and the other SRTP), the device performs RTP-
SRTP transcoding. To transcode between RTP and SRTP, the
following prerequisites must be met:

At least one supported SDP "crypto" attribute and parameters.

EnableMediaSecurity must be set to 1.
If one of the above transcoding prerequisites is not met, then:

any value other than "As is" is discarded.

if the incoming offer is SRTP, force transcoding, coder
transcoding, and DTMF extensions are not applied.
Defines the handling of SRTP for the SIP entity associated with the IP
Profile.

[-1] Not Configured = Applies the settings of the corresponding
global parameter, MediaSecurityBehaviour.

[0] Preferable = (Default) The device initiates encrypted calls to
this SIP entity. However, if negotiation of the cipher suite fails, an
unencrypted call is established. The device accepts incoming calls
received from the SIP entity that don't include encryption
information.

[1] Mandatory = The device initiates encrypted calls to this SIP
entity, but if negotiation of the cipher suite fails, the call is
terminated. The device rejects incoming calls received from the
SIP entity that don't include encryption information.

[2] Disable = This SIP entity does not support encrypted calls (i.e.,
SRTP).

[3] Preferable - Single Media = The device sends SDP with a
single media ('m=') line only (e.g., m=audio 6000 RTP/AVP 4 0 70
96) with RTP/AVP and crypto keys. The SIP entity can respond
with SRTP or RTP parameters:

If the SIP entity does not support SRTP, it uses RTP and
ignores the crypto lines.

If the device receives an SDP offer with a single media (as
shown above) from the SIP entity, it responds with SRTP
(RTP/SAVP) if the EnableMediaSecurity parameter is set to 1.
If SRTP is not supported (i.e., EnableMediaSecurity is set to
0), it responds with RTP.

If two 'm=' lines are received in the SDP offer, the device
prefers the SAVP (secure audio video profile), regardless of
the order in the SDP.
Note:
440
Mediant 500L Gateway & E-SBC
Description
Document #: LTRT-10532