Interworking Dtmf Methods; Interworking Rtp Redundancy; Interworking Rtcp Attribute In Sdp; Interworking Crypto Lifetime Field - AudioCodes E-SBC User Manual

CHAPTER 30 SBC Overview

Interworking DTMF Methods

The device supports interworking between various DTMF methods such as RFC 2833, In-Band
DTMF's, and SIP INFO (Cisco\Nortel\Korea). By default, the device allows the remote user agents
to negotiate (in case of RFC 2833) and passes DTMF without intervention. However, if two user
agents (UA) support different DTMF methods, the device can interwork these different DTMF
methods at each leg.
This DTMF interworking feature is enabled using IP Profiles (ini file parameter IPProfile):
■ SBCRFC2833Behavior - affects the RFC 2833 SDP offer-answer negotiation:
● [0]: (default) the device does not intervene in the RFC 2833 negotiation.
● [1]: each outgoing offer-answer includes RFC 2833 in the offered SDP (the device adds
RFC 2833 only if the incoming offer does not include RFC 2833).
● [2]: the device removes RFC 2833 from the incoming offer.
■ SBCAlternativeDTMFMethod – the device's first priority for DTMF method at each leg is RFC
2833. Therefore, if a specific leg negotiates RFC 2833 successfully, then the chosen DTMF
method for this leg is RFC 2833. For legs where RFC 2833 is not negotiated successfully, the
device uses the parameter to determine the DTMF method for the leg.
The chosen DTMF method determines (for each leg) which DTMF method is used for sending
DTMF's. If the device interworks between different DTMF methods and one of the methods is In-
band\RFC 2833, detection and generation of DTMF methods requires DSP allocation.

Interworking RTP Redundancy

The device supports interworking of RTP redundancy (according to RFC 2198) between SIP
entities. Employing IP Profiles, you can configure RTP redundancy handling per SIP entity:
■ Generate RFC 2198 redundant packets (IpProfile_RTPRedundancyDepth parameter).
■ Determine RTP redundancy support in the RTP redundancy negotiation in SDP offer/answer
(IpProfile_SBCRTPRedundancyBehavior parameter). If not supported, the device discards
RTP redundancy packets (if present) received from or sent to the SIP entity.
For more information, see the above parameters in

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
Profiles).

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
IP Profiles).

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.
Mediant 1000 Gateway & E-SBC | User's Manual
Configuring IP Profiles.
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Configuring IP
Configuring