Configuring a Bandwidth SIP Trunk

Step 1: Create your SIP Trunk

1. Sign in to your portal using the credentials provided by Bandwidth during sign up. You will need to contact Bandwidth to create an account.
2. Click “Account” and select “Sub-Accounts” from the left hand menu.
3. Click “Create Sub-Account” and fill in the required information.
4. Navigate to “Locations” from the left hand menu to create a location.
5. Click on “Voice” from the menu and scroll down to “Origination Settings”.
6. Add your static public IP and SIP Port in the “Voice IP addresses / DNS hosts”.
7. Contact your account administrator to add your public IP address in the “Termination Settings”. Proceed with the next steps while you wait.

8. Click on “Numbers” and select your type and preferences.
9. During the checkout process, assign the numbers to your Sub-Account and location.

Step 2: Configuring your SIP Trunk with 3CX

1. Go to the 3CX Web client and follow the guide on how to configure a SIP trunk.
2. Enter the main trunk number as E164. For example if your number is (888)-233-5678, it should be entered as +18882335678
3. Once your SIP Trunk is ready you will receive a pair of IP addresses from Bandwidth.
4. Add one under “General” -> “Registrar /Server”. The other under “Options” -> “Alternative Proxy”.
5. Bandwidth is an IP-based trunk, so no Authentication ID and Authentication Password are needed. Scroll to the top of the page and press OK to apply the changes and save the trunk.

Step 3: Configure a Number for SMS/MMS.

1. Create an Application:

1. Login to Bandwidth portal.
2. Go to “Applications” and select “+Create Application”.
3. Fill in the “Application name”, select “Messaging” as the application type.
4. Enter the 3CX Webhook URL from the SMS section in 3CX.  
5. Enable all the “Status Callback Types”.
6. Click on “Save” and take note of the “Application ID”. This becomes automatically populated once the application is created.
7. Navigate to the section “Associated Locations” below the application form and select your location from the drop down menu.
8. Select your location and navigate to the “Messaging” tab, enable the “SMS/MMS”, “V2 Messaging”, select the application you created and save changes.

2. Associate the number you want to use for SMS with the newly created Location.

1. Navigate to the “Numbers > My Numbers” and find the number you want.
2. Click your number. Under the “Move Number” select the Sub-Account and the newly created “Location” and click on “Move Number”.

3. Create API Credentials

1. Navigate to “Account” and select “API Credentials”
2. Click the “+Add” button
3. Give it a name and under “Account Scope” select “Basic Access”
4. For Secret Expiration date select “Secret does not expire”
5. Select your account from the “Accounts” drop down
6. Under “Roles” select “Configuration”
7. Click “Save” and make a note of the client ID and the client secret.

4. Return to the 3CX Admin Console and fill in the form in the SMS section with the following information:

1. Client ID - The API client ID created in the previous step
2. Client Secret - The client secret created in the previous step.
3. App ID - Application ID of previously created application.
4. Account ID - Account ID found at the top left corner of the Bandwidth portal in brackets.

Important: According to US legislation (A2P 10DLC SMS), SMS numbers must be registered with a wireless carrier to avoid being blocked. This only applies to A2P numbers (Application to People) and not P2P (People to People). Follow this guide to register your phone numbers

About Bandwidth

For over 20 years, Bandwidth has worked to create a platform that enables customers to effectively live, work and communicate. With their extensive industry experience and modern software-driven approach, they are able to provide a simple, scalable and affordable SIP trunking solution which is now fully supported for use with 3CX PBX.

Last Updated

This document was last updated on 18 June 2026

https://www.3cx.com/docs/sip-trunk/bandwidth-usa/