Create a SIP Trunk on Twilio for Vomyra
This guide walks you through creating and configuring a Twilio Elastic SIP Trunk to work with Vomyra's Voice AI platform. You will configure termination (for outbound calls), origination (for inbound calls), and associate your Twilio phone numbers with the trunk.
Prerequisites
Make sure you have the following ready before starting:
Twilio Account
A Twilio account is required to create trunks. Sign up for Twilio if you don't have one. A free trial can be used for initial testing.
Phone Number
You need at least one Twilio phone number. Buy a number from the Twilio Console. This will be associated with your trunk.
Vomyra Account
An active Vomyra account with SIP trunking access enabled. Contact support@vomyra.com if you don't have access yet.
98.70.52.39. Keep this handy.Create a New SIP Trunk
Navigate to Elastic SIP Trunking
Log in to the Twilio Console and navigate to Elastic SIP Trunking → Trunks in the left sidebar.
Create the Trunk
Click Create new SIP Trunk and enter a friendly name for your trunk:
Vomyra Voice AI TrunkClick Create. Twilio will assign a unique Trunk SID (e.g., TKxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx). Note this down for reference.
Configure Termination (Outbound Calls)
Termination settings control how Vomyra sends outbound calls through Twilio to the PSTN. You need to set up a Termination URI and configure authentication so Twilio knows the requests are legitimate.
Set the Termination URI
Go to the Termination tab in your trunk's configuration. Enter a unique domain name in the Termination URI field:
vomyra-trunk.pstn.twilio.comClick Save. This URI is the gateway address you will provide to Vomyra when registering the trunk.
{your-name}.pstn.twilio.com. This must be unique across all Twilio accounts.Create an IP Access Control List (ACL)
An IP ACL tells Twilio which IP addresses are allowed to send SIP traffic to your trunk. You need to add Vomyra's SIP server IP so Twilio accepts call requests from Vomyra. In the Authentication section, find IP Access Control Lists:
- 1Click Create IP Access Control List
- 2Enter a friendly name:
Vomyra SIP Server - 3Click Create, then click Add IP Address and fill in:
| Field | Value | Notes |
|---|---|---|
| Friendly Name | Vomyra Production | A label for this IP entry |
| IP Address | 98.70.52.39 | Vomyra's SIP server IP |
| CIDR | 32 | Single IP address (no range) |
- 4Save and then associate this ACL with the trunk by selecting it from the dropdown on the Termination page.
403 Forbidden error. Your calls will fail to connect.Create a Credential List (Recommended)
In addition to IP-based security, Twilio recommends also using credential-based authentication. When configured, Vomyra will include a username and password with every outbound call request. In the Authentication section, find Credential Lists:
- 1Click Create Credential List
- 2Enter a friendly name:
Vomyra Credentials - 3Add a username (e.g.,
vomyra_trunk) and a strong password - 4Click Create, then associate the Credential List with the trunk
Configure Origination (Inbound Calls)
Origination settings control how Twilio delivers inbound calls (calls from the PSTN) to Vomyra's SIP server. This is what enables your AI agent to answer incoming phone calls.
Add Vomyra's SIP URI as the Origination URI
Go to the Origination tab in your trunk's configuration. Click Add new Origination URI and fill in:
| Field | Value | Notes |
|---|---|---|
| Origination SIP URI | sip:98.70.52.39:5060 | Where Twilio sends incoming calls (Vomyra's server) |
| Priority | 10 | Lower number = higher priority. Use 10 for primary. |
| Weight | 10 | Load balancing weight. Use 10 for a single trunk. |
| Enabled | Yes | Must be enabled for calls to route |
General Settings
These settings apply to the entire trunk and affect both inbound and outbound calls.
Disable Secure Trunking (SRTP)
Go to the General tab. Find Secure Trunking and set it to Disabled. Click Save.
Enable Symmetric RTP
Set Symmetric RTP to Enabled and save. This helps prevent one-way audio issues that can occur due to NAT (Network Address Translation) between Twilio's and Vomyra's servers.
Configure Call Recording (Optional)
If you want Twilio to record calls on its side, choose your preference:
- Do Not Record (default) — No recording on Twilio
- Record from ringing — Recording starts when the phone rings
- Record from answer — Recording starts when the call is answered
Associate Phone Numbers
You need to associate at least one Twilio phone number with your trunk. This tells Twilio to route calls to that number through your SIP trunk instead of handling them with TwiML or Studio.
Open the Numbers Tab
In your trunk's configuration page, click the Numbers tab.
Associate an Existing Number
If you already have a Twilio phone number:
- 1Click Associate a Number with this Trunk
- 2Select your phone number from the list
- 3The number's Voice configuration will automatically be updated to SIP Trunking
Verify the Number Configuration
To confirm everything is set up correctly:
- 1Go to Phone Numbers → Manage → Active Numbers in the Twilio Console
- 2Click on your number
- 3Under Voice Configuration, confirm that Configure With is set to SIP Trunk and the correct trunk name is shown
Configuration Summary
Here is a complete reference of everything you configured:
| Setting | Value |
|---|---|
| Trunk Name | Vomyra Voice AI Trunk (or your chosen name) |
| Trunk SID | TKxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx (auto-assigned) |
| Termination URI | vomyra-trunk.pstn.twilio.com (your chosen domain) |
| IP ACL | Vomyra IP 98.70.52.39/32 in Vomyra SIP Server ACL |
| Credential List | Username + Password (saved securely) |
| Origination URI | sip:98.70.52.39:5060 (Priority: 10, Weight: 10) |
| Secure Trunking | Disabled (SRTP not supported by Vomyra) |
| Symmetric RTP | Enabled |
| Transport | UDP (default) |
| Associated Numbers | Your Twilio phone number(s) |
Next Steps
Your Twilio Elastic SIP Trunk is fully configured. Continue with these guides: