Voxbone provides local, geographical, mobile and toll free phone numbers and converts incoming calls and SMSs to SIP INVITE and MESSAGE flows.

Clearwater supports these flows, and this document describes how to configure Voxbone and Clearwater to work together, and then how to test and troubleshoot.


There are 3 configuration steps.

  1. Configure Clearwater’s IBCF to trust Voxbone’s servers.
  2. Create a subscriber on Clearwater.
  3. Associate the subscriber with a number on Voxbone.

Configuring IBCF

An IBCF (Interconnection Border Control Function) interfaces between the core network and one or must trusted SIP trunks. We will configure Voxbone to send all its traffic to the IBCF, but we first need to configure the IBCF to accept traffic from Voxbone.

Clearwater’s bono component acts as an IBCF. To make things simpler later on, you should configure all of your bono nodes to act as IBCFs.

The IP addresses you need to specify as trusted peers are

The process for configuring trusted peers is described as part of the IBCF documentation.

If you don’t want to configure all your bono nodes as IBCF nodes, you can do so, but will need to take extra steps when configuring Voxbone to ensure that calls are routed to the correct node.

Creating a subscriber

Creating a subscriber for Voxbone use is done exactly as you would normally do so.

Associating the subscriber on Voxbone

For each telephone number you own, Voxbone allows you to configure a SIP URI to which incoming calls will be sent.

  • If, as recommended earlier, all your bono nodes are configured as IBCFs, you can simply use the SIP URI of the subscriber you created above.
  • If only one (or a subset) of your bono nodes are configured as IBCFs, you must ensure that calls are routed to this node by replacing the domain name of the SIP URI with the IP address or domain name of the IBCF node. For example, if your SIP URI was 1234567890@example.com but your IBCF node was, you must use 1234567890@

If you are also using the VoxSMS service for receiving SMSes, you additionally need to configure a VoxSMS SIP URI using the same SIP URI as above.


The Voxbone web UI allows you to make a test call. Alternatively, you can make a normal call through the PSTN to your Voxbone number.

The only way to test SMS function is to actually send an SMS to your Voxbone number.


If your call or SMS doesn’t get through, there are three things to check.

  • Does the SIP message actually reach the IBCF? You can check this using network capture (e.g. tcpdump) on the IBCF? If not, the problem is likely to either be that the SIP URI’s domain doesn’t resolve to your IBCF, or that security groups or firewall rules are blocking traffic to it.
  • Is the SIP message trusted? You can again check this with network capture - if you see a 403 Forbidden response, this indicates that the IBCF does not trust the sender of the message. Check the trusted_peers entry in your /etc/clearwater/user_settings file and that you have restarted bono since updating it.
  • Would the call go through if it were sent on-net? Try making a call to the subscriber from another subscriber on Clearwater and check that it goes through (or follow the standard troubleshooting process).