Integration with PSTN SIP trunks, known as VoiceConnect, provides inbound and outbound calling to and from the global telephone network for your organization.

VoiceConnect (integration with PSTN SIP trunks) is an optional extra on your StarLeaf account.

To set up a custom configuration with your SIP trunk or session border controller (SBC) requires a high level of expertise.

On this page:

About custom SIP trunk configuration

If the PSTN SIP trunk provider that you want to use is not listed in the providers currently supported by StarLeaf, you can configure a custom SIP trunk through the StarLeaf Portal.

In a custom configuration, you can either:

  • Connect directly to a SIP trunk or
  • Connect to a SBC (session border controller)with a SIP trunk behind it


  • Enhanced StarLeaf Support
  • Either a StarLeaf rooms or VoiceConnect license

How to configure a custom PSTN SIP trunk

In this section:

Step one: Enable custom PSTN SIP trunks

Request StarLeaf Support to enable custom PSTN SIP trunks for your organization.

Step two: Configure sites and hunt groups

Consider your requirements and what you are trying to achieve. For more information on what you can do with StarLeaf, refer to About PSTN SIP trunks, Sites, and Hunt groups.

A site determines the location of any telephone numbers on the trunk. That is, you cannot change the country or area code for a telephone number on a trunk.

Step three: Configure the custom trunk in the StarLeaf Portal

Consider how you want to deploy PSTN if you have multiple sites. Refer to About PSTN SIP trunks; you might want to configure multiple sites in the Portal before you proceed.

To configure the custom trunk in the StarLeaf Portal:

  1. Go to PSTN SIP trunks and choose Add PSTN SIP trunk:
  2. From the Provider drop-down menu, select Custom Provider.
  3. A new custom PSTN trunk profile is created in the Portal:

  4. Complete the fields in the Portal as they are described in the table below:
  5. SettingValueDescription
    NameFree textThe name of the trunk which will be displayed on the user interface for assigning numbers to users/rooms.
    DescriptionFree textDescription of the trunk (optional).


    Free text

    Type the IP address or hostname of the SIP device to which this trunk will connect.

    If this gateway is not listening on the default SIP signaling port (5060), you also need to append the far-end signaling port to the IP address using this format:

    <IP address>:<signaling port>

    For example:

    It is not possible to configure a separate proxy.

    Signalling protocol

    UDP or


    It is expected that it would normally be UDP.

    Ingress numbering scheme

    PSTN local


    PSTN global (E164)

    Configure the numbering scheme for the trunk using the Ingress and Egress numbering schemes.

    Ingress numbering specifies the type of numbers that StarLeaf expects for the calls that it will route onto this trunk. Ensure that any calls that StarLeaf will route to this trunk will be of the correct called number type for the trunk, otherwise the call will fail.

    Note: In most cases, ingress numbering and egress numbering will use the same setting; only configure these with different settings if the device at the other end of the trunk has particular requirements that you must accommodate.

    Select one of:

    PSTN location specific: The trunk expects to receive PSTN numbers in a local or national format. A local PSTN number is one that can be interpreted by a local PSTN. That is, it needs the geographical context of its local PSTN to be meaningful. For example, 01923 778899 is a valid telephone number when considered in combination with a UK location. Similarly, 778899 is a valid telephone number when considered in combination with a Rickmansworth, UK location. A PSTN local number is one that is a national or local telephone number. The dial plan rule that routes calls to this trunk needs to have a Called number type of PSTN local numbers

    PSTN global (E.164): The number that the trunk expects is a fully-qualified international PSTN number. If you have a trunk connecting to a service that expects to receive dialed numbers as fully-qualified E.164 numbers, you must select this option. The dial plan rule that routes calls to this trunk needs to have a Called number type of PSTN global (E.164). The STPBX will use the location settings of the trunk to add the necessary international dialing code to the called number that it receives from the dial plan. Note that it will not include a + prefix

    Egress numbering scheme

    PSTN local


    PSTN global (E164)

    Supported CodecsAAC, DTMF, G.711A, G.711U, G.722, G722.1, H.224, H.239, H.263, H.264, H.264 HVC Lync, iLBC, RDP, SIP Content, and/or VP8

    Select one audio codec out of G.711A, G.711U, and G.722.

    G.711 is used internally so is preferred.

    G.711U is used in North America and Japan; G.711A is used in most other countries.

    Normally DTMF should be selected. This requires the provider to support RFC2833.

    The other codecs should not be selected.

  6. Add the telephone numbers that you have bought from the provider. For each number that you have purchased, enter authentication details from your SIP trunk provider. What you enter here varies from provider to provider . You might need to contact StarLeaf Support for help.
    • Registration name: Sometimes this is the telephone number, a username, or an account number and sometimes this is not required
    • Extension authentication: You must enter a value here. It will be the same as the Registration name (unless that is empty). Often it is the username or the telephone number, but sometimes it is an account number
    • Extension password: The password for the telephone number
  7. Notice that the numbers are currently not Assigned. Complete the next step.

Step four: Assign the PSTN numbers

  1. In the StarLeaf Portal, go to PSTN SIP numbers. You will see all the numbers that you have purchased and added to your configured trunks. For each PSTN number you can configure these settings:
    • Target: Choose a user, room system or hunt group to be the target for a PSTN number. This means that any incoming calls to this number will be routed to the chosen user, room system or hunt group. It also means that outgoing calls from the target, where that is a user or a room, will use the PSTN number as the caller ID. Note that members of hunt groups will not use the target as their outgoing caller ID and will instead use either their own target number if they have one, or the site default if there is one, or the organization default
    • Site default: You can choose one PSTN number per site to be the site default. This means that all outgoing calls from the site will use this number as their caller ID (unless the room or user making the call is a target for another PSTN number)
    • Organization default: You can choose one PSTN number to be the organization default. This will be used as the caller ID where the user or room both does not have a site default and is not a target for another PSTN number
  2. Click Apply.

You can also assign PSTN numbers through the Users > Edit, the Room systems > Edit, and the Hunt groups > Edit pages.

Assigned PSTN numbers do not automatically appear in the directory, however if necessary, you can add these by editing the details for a room, user, or hunt group. For example, you can add the PSTN number as a user’s Work number.


There are some limitations of this GUI for setting up PSTN SIP Trunks. These apply only to custom SIP trunk configurations; they do not apply to configurations using SIP trunks that are in the StarLeaf-supported list of providers.

  • It is not possible to specify a separate proxy from the gateway address.
  • When using Igress/Egress global numbering, there is no option to include a + prefix.
  • Caller ID is taken as the registration name for each number.
  • StarLeaf always connects from source port 5376.
  • StarLeaf sends a separate registration for each configured line including the contact header (also known as binding address) containing the PSTN global (E.164) with +. Correspondingly, StarLeaf expects calls to be addressed to [email protected]_ip_address