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Agents you build on Wixzel Voice place and answer phone calls over a SIP trunk you bring, and Twilio Elastic SIP Trunking is one of the carriers that works with it. Twilio bills you for the trunk and the minutes at your own rates; the voice engine is billed per second of actual usage from your Wixzel Voice balance. This page covers where Twilio keeps each setting. The steps that are the same for every carrier, and the troubleshooting list, are on SIP trunks.
Allowlist 95.216.218.102 for outbound calls, and send inbound calls to sip:95.216.218.102:5090. Every trunk returns both as platform_ip and origination_uri, so read them from GET /v1/sip-trunks rather than trusting this page to stay current.

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How do I connect a Twilio SIP trunk to Wixzel Voice?

Twilio authorises outbound calls by source IP, and rejects anything else instantly.
1

Open the trunk's termination settings

Elastic SIP Trunking → your trunk → Termination → Authentication.
2

Add the platform IP to an IP Access Control List

Create or edit an IP ACL and add 95.216.218.102. A Credential List works instead, if you would rather authenticate with a username and password: put those on the trunk’s username and password fields and Wixzel Voice will use them in place of IP auth.
3

Check the Termination SIP URI matches the trunk host

The host on your Wixzel Voice trunk must be the same your-domain.pstn.twilio.com shown in the console.
4

Confirm the caller ID is a number on that account

Twilio rejects a from_number_id it does not own.
5

Set the Origination URI, for inbound

Elastic SIP Trunking → your trunk → Origination, then add an Origination SIP URI of sip:95.216.218.102:5090, or whatever GET /v1/sip-trunks reports as origination_uri.Outbound works without this; inbound does not, and does not complain. Attach your numbers to the trunk in the same console, then give the number an inbound_agent_id in Wixzel Voice so there is an agent to answer them.
Twilio expects the leading + on the number, so leave send_plus at its default.

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What does a missing Twilio IP ACL entry look like?

A missing IP ACL entry shows up as an immediate rejection, roughly a second after the call is placed, with hangup cause 21 (Call Rejected). It does not ring and it does not time out. If a Twilio call fails some other way, work through When a call does not connect, and start with Twilio’s own call logs.
  • SIP trunks: the allowlist, the inbound address and the troubleshooting list that apply to every carrier.
  • Quickstart: connect the trunk, register a number, create an agent and place a first call.
  • Twilio SIP trunk setup: the short version on the Wixzel Voice site, with what a minute costs on each voice engine.