[asterisk-users] Is 100 trying mandatory? Can asterisk answer with 180 without prior 100 trying?

Benoit Panizzon benoit.panizzon at imp.ch
Tue Mar 20 07:25:36 CDT 2018

Hi Tryba

> A (very) dirty workaround would be to drop these packets with iptables
> (assuming Linux as OS), something like:
> iptables -t raw -I OUTPUT -p udp -d ipaddrofpbx -m string --algo bm
> --from 0 --to 32 --string "SIP/2.0 100 " -j DROP
> Don't try it with TCP :)


Indeed, this is what I did with a Mikrotik Firewall that is in front
of the * Server: Drop UDP packet with content starting with "SIP/2.0
100 Trying"

And this showed, that not the missing 100 Trying is tripping our SBC.
So I contacted the Vendor who had a quick look at the 181 Ringing which
is not being relayed and found that the issue was the Contact: Header
containing two line= attributes.

So I'm now trying to contact the vendor of that other PBX to figure
out, why it is sending two line= attributes as part of the contact

Mit freundlichen Grüssen

-Benoît Panizzon-
I m p r o W a r e   A G    -    Leiter Commerce Kunden

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