Twilio Elastic SIP Trunking

Use this guide for an existing Twilio number. To purchase a Verbatik-managed number instead, use Buy a phone number.

Create the Twilio trunk

1. In Twilio Console, open Elastic SIP Trunking and create a trunk.
2. Configure Termination. Create a termination domain and choose a regional edge appropriate to the gateway. An example is your-trunk.pstn.ashburn.twilio.com; use your actual domain.
3. Attach a SIP credential list, or configure IP authentication using the Verbatik gateway’s approved public egress IP. Request that value from Verbatik if the setup guide does not show it.
4. Configure Origination with the Verbatik inbound SIP URI from SIP setup. Match the transport.
5. Under the trunk’s Numbers, link the Twilio number you control. Check its existing Voice routing before replacing it.

Import into Verbatik

1. Open Phone numbers → Connect to your number via SIP trunking and select Twilio.
2. Enter the number in E.164 format and your Twilio termination URI.
3. Enter the credential-list username and password. Do not use your Account SID and Auth Token in these fields.
4. Add Twilio’s current signaling CIDRs under Additional settings, choose matching transport/codecs and leave registration off for an Elastic trunk.
5. Save, assign a published voice agent, then run the verification steps below.

Check permissions and behavior

Twilio Elastic SIP Trunking geographic permissions must allow the countries you plan to call. Any carrier REFER-based transfer route needs its corresponding trunk permissions; a saved transfer destination alone does not grant carrier permission.

Test an incoming call and two-way audio first. Then test the configured staff transfer, rejected/no-answer transfer recovery and outbound calls if your account is enabled for them. Keep the previous route available until these checks pass.

Twilio retains ownership and billing of this number. SIP setup does not buy, release or port it. Messaging routing is separate.

Carrier console details and ranges can change. Use Twilio’s SIP Trunking documentation and current network addresses as the carrier reference.