Basic SIP NAT Traversal Question

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Hi all,

Checking on the asterisk source code I’ve seen that SIP will always use the IP address in the “c=” field of SDP to send media. Is that correct?

Is there a case where asterisk would send media to the received source IP
address instead of the one he got on the SDP?

I know the externip and localnet config, but it seams that this only changes the media IP address that asterisk informs on his SDP.

The only way to solve it would be the endpoint be using STUN/ICE or I’m missing something?

scenario: endpoint inform his LAN address on his SDP and asterisk send media to it, no audio. asterisk=DMZ
endpoint behind NAT
[general]
externhost setted localnet setted

[endpoint]
nat=yes

Thanks, Gabriel