Help: Can't get NAT to work with a specific VoIP protocol. Stumped.

Juniper SRX Reviews

Last Post by emilyf 3 months ago

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emilyf

(@emilyf)

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Topic starter 17/07/2026 11:44 pm [#10047]

Hi everyone. I’m setting up a Juniper SRX300 for our small office, trying to get our VoIP phones working through it. I have a basic source NAT rule set up for our LAN to WAN traffic, and it works fine for web browsing and email.

But our VoIP calls keep failing. The provider uses SIP over TLS on a non-standard port. I think the ALG might be interfering, or maybe my NAT isn’t handling the SIP signaling correctly. I’ve tried disabling the SIP ALG, but the calls still don’t connect. Has anyone run into this with a specific VoIP provider? What should I check next?

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