Twilio inbound odd behavior

[cloidhamer]

I followed the instructions for Twilio on the 3CX website. Outbound calls work no problem, but inbound calls are not working. I used the 3CX template to create the SIP trunk and under Type of Authentication I left Do Not Require - IP Based, but I put in the Authentication info like it says in the instructions "CREDENTIAL LIST - which needs to be entered into 3CX even if the provider settings would indicate the trunk is IP based."
So when a call comes
the extension rings
I pick it up, but there is nothing
Hang up
My extension rings again with the same call, picking it and there is nothing
Hang up
Extension rings again

Here is the wierd thing. If I change the Authentication to Register then the calls come in fine, but 3CX fails the trunk "Registration at Twilio has failed.". What did I miss?

 

[YiannisH_3CX]

Hello @cloidhamer

You should leave the trunk set to IP based as authentication will fail if you setup the elastic SIP trunking product. You will also have issues with outbound calling.

Then make an inbound call and check the activity log for details regarding the issue you are facing. You could also run a wireshark capture for more details. It looks like that the call is not actually answered and Twilio is sending a re-invite.
Also make sure that the firewall checker passes all tests and try again