[Freeswitch-users] codec negotiation error

Brian May brian at linuxpenguins.xyz
Wed Aug 10 06:56:24 UTC 2022


After wasting hours on this, I *think* I finally found the problem: My
VDSL modem! Vigor130.

It has a setting "Data Filter" which was enabled. I don't need any sort
of firewall, as this is plugged straight into my EdgeRouter which does
that. So now disabled both "Data Filter" and "Call Filter".

It looks like it should block "TCP/UDP, Port: from 137~139 to 53". So it
shouldn't affect VOIP in anyway. So I didn't worry about testing it.

Turned this setting off, and I can consistently make incoming VOIP
calls. Fingers crossed.

(well once I tested it correctly, put on the correct headset, etc)

Also "Accept large incoming fragmented UDP or ICMP packets (used in some
games and streaming)" is on and "Enable Strict Security Firewall"
doesn't seem to make any difference, so I left that on also.

I really don't understand why non-bridged calls worked fine. But don't
particularly care now.

Now I suspect that the SIP connection tracking will work fine in my
firewall, so my gradually ease back into that. Although I have a
suspicion this will not work correctly with TLS connections.
Brian May <brian at linuxpenguins.xyz>

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