Connect Bandwidth SIP trunk to SessionPBX

Bandwidth supplies US and international numbers and outbound calling over SIP trunks. Bandwidth accounts are set up with a Bandwidth implementation specialist rather than self-serve, and Bandwidth recognises your phone system by IP address only, with no registration or password on a standard trunk.

You bring your own Bandwidth account, numbers and caller ID. SessionPBX doesn’t supply Bandwidth service.

About this guide. The Bandwidth settings on this page were checked against Bandwidth’s published documentation on 19 October 2026. The SessionPBX field names come from the Add SIP trunk wizard in the product. If Bandwidth shows a different value in your account, use theirs.

Before you start

During onboarding, Bandwidth gives you:

• the IP addresses of the two SBCs (session border controllers) that serve your trunk. Bandwidth uses both to send calls to you, and expects you to fail over between them.
• your numbers

Give Bandwidth:

• your SessionPBX region’s IP address from the table below, to allow for outbound calls and to send your incoming calls to
• the request that numbers are sent to you in E.164 format

Bandwidth’s requirements for SIP trunks:

SessionPBX addresses for Bandwidth

Give Bandwidth the address for the region your workspace is hosted in. If you’re not sure which region that is, email support@sessiontalk.co.uk.

SessionPBX accepts calls from carriers on UDP port 5060 or TLS port 5061. TCP isn’t accepted for incoming calls. Calls that SessionPBX sends to Bandwidth can use UDP, TCP or TLS on whatever port Bandwidth specifies.

Add the trunk in SessionPBX

1. Open the SessionPBX project and select Call Routing.
2. On SIP trunks, select Add trunk.
3. Provider: name the trunk, for example Bandwidth, and choose Generic carrier (IP authentication).
4. Connection: set Host to the first Bandwidth SBC IP address, Port to 5060 and Transport to UDP. Leave Direction on Both directions.
5. Authentication: keep By our IP address. Under Carrier IP addresses, list both Bandwidth SBC IP addresses, one per line.
6. Inbound: list your Bandwidth numbers in international format, for example +19192971000.
7. Outbound:
   • Set Caller ID to one of your Bandwidth numbers. Leave Assert caller ID in on From header only unless Bandwidth asks for something else.
   • Under Additional gateways, add the second SBC IP address, for example 192.0.2.11:5060/udp 10, so calls fail over to it. Give a backup gateway priority 10. A lower number wins, so calls use the trunk’s main host (priority 0) first and move to the backup only if the main host stops answering. A backup left at priority 0 shares calls with the main host instead.
8. Select Create trunk.

Route your numbers

On Call Routing, use Inbound number routing to choose where each number rings: everyone, a team member, a ring group, a call queue or a call flow. See Phone Numbers & Outbound Calls.

Allow members to call out

Outbound calling is off for new members. Open Team Members, edit the member, turn on Outbound PSTN under Access & features, and select Save member.

Members can dial numbers in international format, such as +447700900123. SessionPBX sends the number to Bandwidth in international format.

Test the trunk

1. Call one of your Bandwidth numbers from an outside phone and check that the right destination rings.
2. With Outbound PSTN on for one member, call a public number. Check that audio works both ways and that the called phone shows the caller ID you expect.
3. If you call into an IVR, check that key presses work. SessionPBX sends and receives key presses as RFC 2833 telephone events.

If calls fail, email support@sessiontalk.co.uk with the time of the call, the number you called from and the number you called.

Sources

• Bandwidth: PBX integration guide 
• Bandwidth: Customer self service for IP whitelisting 
• Bandwidth: IP whitelist (developer docs)