AudioCodes Mediant 1000B - Interworking RTCP Attribute in SDP; Interworking Crypto Lifetime Field; Fax Negotiation and Transcoding

Version 7.2 665 Mediant 1000B Gateway & E-SBC
User's Manual 29. SBC Overview
the device discards RTP redundancy packets (if present) received from or sent to the
SIP entity.
For more information, see the above parameters in ''Configuring IP Profiles'' on page 423.
29.5.9.3 Interworking RTCP Attribute in SDP
The device supports interworking the RTCP attribute 'a=rtcp' in the SDP between SIP
entities. Employing IP Profiles, you can configure RTCP attribute handling (add, remove or
transparent) per SIP entity, using the IpProfile_SBCSDPHandleRTCPAttribute parameter
(see ''Configuring IP Profiles'' on page 423).
29.5.9.4 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 423).
29.6 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
423.