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How Firewall pinholing works for SIP

i would like to understand how pinholing works on Cisco Firewalls. I am from teleresence background.
We use SIP as a protocol to make video calls. i have read about problems which sip has traversing NAT.
protocols like h460 17/18/19 are used to fix this issue.
As per my understanding > any thing from private to public is allowed.

so suppose a user A Video endpoint dials user B Video End point on public internet.
how will a pinhole for signaling and media will be created.
Also what happnes if user B shares presentation and traffic comes from public to private network.
how does a firewall takes care of that.

Please help me understand on layman terms.

Thank you in advance.


  • Firewalling
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