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% set profiles signaling ipSignalingProfile <SIP profile name> ingressIpAttributes flags suppress183For3xxRedirectResponsek <disable | enable>
% set profiles signaling ipSignalingProfile <SIP profile name> ingressIpAttributes flags suppress183WithoutSdp <disable | enable>

Passing Audio Codecs in SDP Offer

The 

The

Late Media INVITE or Re-INVITE Support

Example 1: G711 pass-through call

1. Ingress Offer: G711, G729
2. Egress Offer: G711, G729, AMR, G726
3. Ingress Answer: G711
4. Egress Answer: G711

If the

Example 2: G711 to AMR transcoded call

1. Ingress Offer: G711, G729
2. Egress Offer: G711,G729, AMR, G726
3. Egress Answer: AMR
4. Ingress Answer: G711
   If the 

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   receives an re-INVITE with no SDP  on egress, by default, the

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    generates an offer for AMR. If the “Send All Allowed Codecs For Late Media Invite Or Re-Invite” flag is in enabled state, then the

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    generates a codec list of G711,G729, AMR, and G726 in the offer.

The SBC has an existing flag for late media INVITEs or Re-INVITES which specifies the included codecs in the SDP offer, but the behavior differs based on whether the base call is a pass-through or transcoded call. For pass-through calls, the codecs offered do not include those supported for transcoding. For certain scenarios, the originator of the INVITE/Re-INVITE must know the full capabilities even for a pass-through call. This feature addresses the pass-through case where the full set of codecs is needed.

When the sendSBCSupportedCodecsForLateMediaReInvite flag is enabled, the SBC sends all the codecs supported on a particular leg as an SDP OFFER in the 200 OK response to a late media Re-INVITE. The OFFER sent in the 200 OK contains all the pass-through and transcodable codecs supported on that leg. This behavior is applicable only for late media Re-INVITE requests. The flag does not have any impact on late media INVITE requests.

For example, the

Refer to Common IP Attributes - SIP - CLI or Common IP Attributes - Flags (EMA) for configuration details.

Late Media Pass-through Calls over GW-GW

The SBC supports late media pass-through calls over GW-GW and also handles late media (offer-less) re-INVITEs on either side. This functionality is supported when the flag lateMediaSupport is configured as passthru.

set addressContext <addressContext name> zone <zone name> sipTrunkGroup <sipTrunkGroup name> media lateMediaSupport passthru

When the flag lateMediaSupport is set as passthru, a late media INVITE/re-INVITE received on one leg is relayed to the other leg.

ANAT Support

Alternative Network Address Types (ANAT) semantics for the SDP grouping framework allows the expression of alternative network addresses (for example. different IP versions) for a particular media stream. This ability is useful in environments with both IPv4-only hosts and IPv6-only hosts.

The 

Anchor
Ice-Lite Ice-Lite

ICE-Lite Support

Bundling of Streams

The

The SDP media-level attribute, "bundle-only", is parsed and used to identify that specific media is only used if bundled and resides within a BUNDLE group. The "bundle-only" attribute is a property attribute with no value.

The use of a BUNDLE group and a BUNDLE address also allows the usage of a single set of Interactive Connectivity Establishment (ICE) candidates for multiple "m=" lines.
If using RTP/RTCP multiplexing, use the same address:port combination for all RTP and RTCP packets.

Single-bundle

The

Stream

• You can tag a stream as 'bundle-only' with the port set to '0'.

• The policers for the stream, which represents the bundle reflect the total bandwidth for all streams within the bundle.
• Only relay scenarios are supported; any interworking causes the streams to unbundle.

Bundle Only

The 

• Offers with "m=" lines tagged as bundle-only with the port set to 0.
• Non-compliant offers which associate bundle-only with a non-zero port, the "m=" line is also accepted; the 

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  treats the stream as a bundle-only stream.
• The 

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  handles media attributes received with a bundle-only stream offer, taking into consideration the stream is present, as well as the output in the outbound offers (For example, media codecs and fmtp options).
• The  handles the media attributes received with a bundle-only stream offer taking into consideration that the stream is present and output in the outbound offers. For example; media codecs, fmtp options)

Bundle Group

The 

• The OFFER contains the BUNDLE attribute followed by a list of streams, which are part of the BUNDLE.
• The OFFER contains a unique address:port combinations for each stream as the peer may not support bundling the streams.

If the peer supports the bundle:

• The ANSWER contains the BUNDLE attribute.
• The ANSWER contains the same address:port combination for all streams within the bundle.

OFFER and ANSWER

The following is an example for OFFER and ANSWER mechanism.

OFFER

v=0
o=alice 2890844526 2890844526 IN IP4 10.32.241.3
s= 
c=IN IP4 10.32.241.3 
t=0 0 
a=group:BUNDLE audio video 
m=audio 10000 RTP/AVP 0  
a=mid:audio
a=rtpmap:0 PCMU/8000 
a=extmap 1 urn:ietf:params:rtp-hdrext:sdes:mid 
m=video 10002 RTP/AVP 31 32
a=mid:video 
a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000
a=extmap 1 urn:ietf:params:rtp-hdrext:sdes:mid 

ANSWER

v=0 
o=bob 2808844564 2808844564 IN IP4 biloxi.example.com 
s= 
c=IN IP4 biloxi.example.com 
t=0 0 
a=group:BUNDLE audio video 
m=audio 20000 RTP/AVP 0  
a=mid:audio
a=rtpmap:0 PCMU/8000 
a=extmap 1 urn:ietf:params:rtp-hdrext:sdes:mid 
m=video 20000 RTP/AVP 32 
a=mid:video 
a=rtpmap:32 MPV/90000
a=extmap 1 urn:ietf:params:rtp-hdrext:sdes:mid 

Interactions with Security

Bundling is only allowed when security is relayed, and:

• DTLS-SRTP and DTLS-SCTP for data are relayed
• SDES SRTP is relayed

Limitations

• You can only relay (not interwork) bundling.
• Configuration for LI or a call requiring transcoding, DTMF, or security termination is unbundled.
• Bundling is not supported over the gateway protocol.

RTP and RTCP Multiplexing

The

Within a BUNDLE group, the offerer and answerer must enable RTP/RTCP multiplexing for the RTP-based media associated with the BUNDLE group.

When RTP/RTCP multiplexing is enabled, the

• The

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   allows relay of multiplexed RTP and RTCP traffic only when it supports the rtcp-mux  on both sides of the call.
• The "a=rtcp-mux" attribute negotiates multiplexing when RTCP is enabled on both sides of the call.
• The rtcp-mux attribute takes precedence over the "a=rtcp:" attribute when it has to accept SDPs from the peer.
• When the

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  uses rtcp-mux within a bundle, rtcp-mux is enabled for all streams in a bundled or disabled for all.

Interactions with ICE

Using media stream bundling and RTCP multiplexing ensures that only a single ICE transaction on one port is required. This limits the occurrence of NAT traversal issues and reduces the time needed to establish a call.

For the OFFER:

• The ICE data is unique for each stream.
• A candidate is included for RTCP in the initial OFFER and for the RTP.
• A bundle-only "m=" line does not include an ICE candidate or ufrag/pwd.

For the ANSWER:

• The ICE data matches the chosen master stream.
• A single ICE candidate line is included for the RTP component