Interworking Crypto Lifetime Field; Interworking Media Security Protocols; Interworking Ice Lite For Nat Traversal; Fax Negotiation And Transcoding - AudioCodes Mediant 4000 SBC User Manual

User's Manual

20.5.9.5 Interworking Crypto Lifetime Field

The device supports interworking the lifetime field in the 'a=crypto' attribute of the SDP,
between SIP entities. Employing IP Profiles, you can configure the lifetime field handling
(remove or retain) per SIP entity, using the IpProfile_SBCRemoveCryptoLifetimeInSDP
parameter (see ''Configuring IP Profiles'' on page 384).

20.5.9.6 Interworking Media Security Protocols

The device supports interworking media security protocols for SRTP, between SIP entities.
Employing IP Profiles, you can configure the security protocol (SDES, DTLS or both) per
SIP entity, using the IPProfile_SBCMediaSecurityMethod parameter (see ''Configuring IP
Profiles'' on page 384). For more information on SDES and DTLS, see ''Configuring Media
(SRTP) Security'' on page 195.

20.5.9.7 Interworking ICE Lite for NAT Traversal

The device supports interworking ICE for NAT traversal, between SIP entities. Employing
IP Profiles, you can enable ICE Lite per SIP entity, using the IPProfile_SBCIceMode
parameter (see ''Configuring IP Profiles'' on page 384).
20.6

Fax Negotiation and Transcoding

The device can allow fax transmissions to traverse transparently without transcoding or it
can handle the fax as follows:

Allow interoperability between different fax machines, supporting fax transcoding if
required.

Restrict usage of specific fax coders to save bandwidth, enhance performance, or
comply with supported coders. These coders include G.711 (A-Law or Mu-Law), VBD
(G.711 A-Law or G.711 Mu-Law), and T38.
Fax configuration is done in the Coder Groups table and IP Profiles table. The Coder
Groups table defines the supported coders, which is assigned to the IP Profile associated
with the SIP entity. The IP Profiles table also defines the negotiation method used between
the incoming and outgoing fax legs, using the following fax-related parameters:

IPProfile_SBCFaxBehavior: defines the offer negotiation method - pass fax
transparently, negotiate fax according to fax settings in IP Profile, or enforce remote
UA to first establish a voice channel before fax negotiation.

IPProfile_SBCFaxCodersGroupName: defines the supported fax coders (from the
Coder Groups table).

IPProfile_SBCFaxOfferMode: determines the fax coders sent in the outgoing SDP
offer.

IPProfile_SBCFaxAnswerMode: determines the fax coders sent in the outgoing SDP
answer.

IPProfile_SBCRemoteRenegotiateOnFaxDetection: You can also configure the device
to detect for faxes (CNG tone) immediately after the establishment of a voice channel
(i.e., after 200 OK) and within a user-defined interval. If detected, it can then handle
the subsequent fax renegotiation by sending re-INVITE messages to both SIP entities
(originating and terminating faxes). For more information, see the parameter in
''Configuring IP Profiles'' on page 384.
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20. SBC Overview
Mediant 4000 SBC