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To allow Direct Media between NAT devices, or between NAT and Non-NAT devices, the following configuration is necessary.

Caution

Direct Media with NAT will not work under following conditions:

  • If the addressContext name of both the endpoints does not match.
  • If the call is a Lawful Intercepted call.
  • If Direct Media Group ID's do not match, directMediaGroupId should be same on both the Trunk Groups.


Caution

For SIP Direct Media calls, if you enable SIP Trunk Group level flag directMediaAllowed and the Packet Service Profile level flag useDirectMedia, the SBC supports a maximum of four media lines in the received INVITE. If the number of media lines exceeds four, the SBC fails to perform due to error conditions.

Configuring Direct Media Between Endpoints Behind the Same NAT

ACCESS SIDE:

  • At Sip Trunk Group Level
    • directMediaAllowed enabled
    • directMediaAllowedBehindNat enabled
  • At Packet Service Profile Level
    •  useDirectMedia enabled



CORE SIDE (towards Application Server):

  • At IPSP Level
    • sendDirectMediaInfoInSdpAttribute enabled
  • At Packet Service Profile Level
    • useDirectMedia enabled

The dmNatPrefix table is not required to create as the endpoints are behind the same NAT.

Configuring Direct Media Between Endpoints Behind the Different NAT

 ACCESS SIDE:

  • At Sip Trunk Group Level
    • directMediaAllowed enabled
    • directMediaAllowedBehindNat enabled
    • sdpTransparencyState disabled
  • At Packet Service Profile Level
    • useDirectMedia enabled



CORE SIDE (towards Application Server):

  • At IPSP Level
    • sendDirectMediaInfoInSdpAttribute enabled
  • At Packet Service Profile Level
    • useDirectMedia enabled
  • At Address Context Level
    • Creating the table dmNatPrefix on addressContext
    • Adding the signaling IP Address of NAT Box, which can have direct media among them.

Configuring Direct Media Between Endpoints Behind the NAT and Non-NAT Endpoint

This is an occasional scenario where an endpoint behind NAT can have Direct Media with endpoint not behind NAT. However, if such a case exists, SBC exchanges the media IPs of such devices, while the actual exchange of media depends on the network.

ACCESS SIDE:

  • At Sip Trunk Group Level
    • directMediaAllowed enabled
    • directMediaAllowedBehindNat enabled
    • sdpTransparencyState disabled
  • At Packet Service Profile Level
    • useDirectMedia enabled

CORE SIDE (towards Application Server):

  • At IPSP Level
    • sendDirectMediaInfoInSdpAttribute enabled
  • At Packet Service Profile Level
    • useDirectMedia enabled
  • At Address Context Level:
    • Creating dmNatPrefix on addressContext
    • Adding signaling IP Address of,
      • NAT Box
      • Endpoint signaling IP not behind NAT.

The CLI syntax to enable Direct Media with NAPT on Trunk Group is as follows:

% set addressContext <name> zone <name> sipTrunkGroup <TG-Name> media directMediaAllowedBehindNapt <disable|enable>

The CLI syntax to group the endpoint signaling IP addresses for which to allow Direct Media with NAPT is as follows:

set addressContext <name> natDirectMediaGroup <groupName> dmNatPrefix <IpV4_Address> <prefixLen>