Direct Media and Anti-trombone Support for ICE and DTLS

Overview

is enhanced to support ICE and DTLS with direct media and anti-trombone scenarios. Any call, which is setup as Direct Media call can become a non-Direct Media call due to call transfer or Re-INVITE. supports conversion of a Direct Media call to Non Direct media and vice versa and handles the ICE/DTLS interactions as per the following:

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  supports the direct media call between two devices that support ICE procedures and may use DTLS for media. The ICE procedures, connectivity checks, and DTLS procedures occur directly between the endpoints. The direct media works with early dialog (answer in 18x reliable) and/or 200 Ok.
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  sends the following ICE and DTLS parameters are copied from Ingress SDP and sent in Egress SDP for direct media:
  • ICE parameters
    • ice-ufrag
    • ice-pwd
    • ice-lite
    • ice-mismatch
    • candidate

    • remote-candidates
    • ice-options

    • end-of-candidates
  • DTLS parameters
    • setup (active/passive)
    • fingerprint

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  supports the ICE-Lite procedure for a call when it is reconfigured as non-direct media after setting up as a direct media call initially.

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  does not play any role in the ICE procedures for the transfer of a direct media call (that is connected through an AS) to a direct media call to another party except relaying the SDP parameters.

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  supports reconfiguring a call to direct media with end to end ICE procedures after it is setup as non-direct media call using ICE-Lite procedures.

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  supports the transfer of a non-direct media call that used ICE-Lite to a direct media call to another party by Refer mechanism.

Inter-SBC Direct Media Scenarios

In inter-

direct media scenario, the call legs are on different

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s.

The following diagram illustrates inter-

direct media scenario with end to end ICE and DTLS procedure.

Intra-SBC Direct Media Scenarios

In intra-

direct media scenario, both the call legs are on same .

The following diagram illustrates intra-

direct media scenario with end to end ICE and DTLS procedure.

Anti-trombone Direct Media

Anti-trombone direct media uses normal direct media on

facing the endpoints and anti-trombone configuration on the  side facing the SIP AS. This feature is useful when x-dmi cannot be passed through the SIP AS. For more information on media anti-trombone, refer to Media Antitrombone.

ICE Ingress and Egress Compatibility

• DTLS must be enabled on Ingress and Egress Trunk Groups if required for Direct Media.
• ICE must be enabled and compatible between Ingress and Egress Trunk Groups for Direct Media ICE calls.