"Rejecting unknown SIP connection from " weird IP address

I’m seeting up FreePBX with SIP trunking from Twilio. It all works except for periodic failures when calling in to the PBX. When this happens I get a recording “all circuits are busy” and the following error is logged:

[2017-09-26 16:25:31] WARNING[17554][C-0000025f] Ext. s: “Rejecting unknown SIP connection from 217.172.189.87”

I don’t know where this IP address is coming from, since it is not listed as one of the IP’s from which Twilio originates calls. A reverse DNS lookup shows that it is registered in Germany. I thought there might be some NAT problem and I tried various NAT settings on my router, but these all made things worse. I suppose I could just create another trunk for this IP address, since the errors always references this exact address, but I’d like to understand what’s happening --??

Thanks much in advance for your advice.

Matthew Fleming

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If that is happening when you call into your Twilio number, then call Twilio and ask them what happened to the call that you placed to your Twilio number at 2017-09-26 16:25:31 (or whenever you saw a failed call)?

If that IP address is unknown to you, why do you allow traffic from it through your firewall?

Same problem

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