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--- title: include file description: Learn how to use the Azure portal to configure direct routing. services: azure-communication-services author: boris-bazilevskiy ms.service: azure-communication-services ms.subservice: pstn ms.date: 06/01/2023 ms.topic: include ms.custom: include file ms.author: nikuklic --- ## Prerequisites - An Azure account with an active subscription. [Create an account for free](https://azure.microsoft.com/pricing/purchase-options/azure-account?cid=msft_learn). - An active Communication Services resource. [Create a Communication Services resource](../../../quickstarts/create-communication-resource.md). - The fully qualified domain name (FQDN) and port number of a session border controller (SBC) in an operational telephony system. - The [verified domain name](../../../how-tos/telephony/domain-validation.md) of the SBC FQDN. > [!NOTE] > You can find more usage examples for `SipRoutingClient` on [GitHub](https://github.com/Azure/azure-sdk-for-net/blob/main/sdk/communication/Azure.Communication.PhoneNumbers/README.md#siproutingclient). ## Add a session border controller 1. On the left pane, under **Voice Calling - PSTN**, select **Direct routing**. On the **Session Border Controller** tab, select **Configure**. 2. Enter an FQDN and signaling port for the SBC. Requirements for the SBC FQDN include: - The domain part of the FQDN must be verified before you can add it to your direct routing configuration, as mentioned earlier in the [prerequisites](#prerequisites). - The SBC certificate must match the name. Wildcard certificates are supported. - You can't use the `*.onmicrosoft.com` and `*.azure.com` domains for the FQDN. For the full list of requirements, see [Azure direct routing infrastructure requirements](../../../concepts/telephony/direct-routing-infrastructure.md). :::image type="content" source="../media/voice-routing/add-session-border-controller.png" alt-text="Screenshot of adding a session border controller on the panel for configuring direct routing."::: 3. Select **Next**. If everything is set up correctly, you should see the status of SBC as *Active* in Azure portal. [](../media/voice-routing/session-border-controller-connection-properties.png#lightbox) > [!IMPORTANT] > Before placing or receiving calls, make sure that SBC status is *Online* ## Create voice routing rules [](../media/voice-routing/voice-routing-configuration.png#lightbox) Give your voice route a name, specify the number pattern by using regular expressions, and select the SBC for that pattern. Here are some examples of basic regular expressions: - `^\+\d+$`: Matches a telephone number with one or more digits that start with a plus. - `^\+1(\d{10})$`: Matches a telephone number with 10 digits after `+1`. - `^\+1(425|206)(\d{7})$`: Matches a telephone number that starts with `+1425` or with `+1206`, followed by seven digits. - `^\+0?1234$`: Matches both `+01234` and `+1234` telephone numbers. For more information about regular expressions, see [.NET regular expressions overview](/dotnet/standard/base-types/regular-expressions). You can select multiple SBCs for a single pattern. In such a case, the routing algorithm chooses them in random order. You can also specify the exact number pattern more than once. The higher row has higher priority. If all SBCs associated with that row aren't available, the next row is selected. This way, you create complex routing scenarios. ## Remove a direct routing configuration To delete a voice route: 1. On the left pane, under **Voice Calling - PSTN**, go to **Direct routing**. 1. On the **Voice Routes** tab, select the checkboxes for the route (or routes) that you want to delete. 1. Select **Remove**. To delete an SBC: 1. On the left pane, under **Voice Calling - PSTN**, go to **Direct routing**. 1. On the **Session Border Controllers** tab, select **Configure**. 1. Clear the FQDN and port fields for the SBC that you want to remove, and then select **Next**. 1. On the **Voice Routes** tab, review the voice routing configuration. Make changes if needed, and then select **Save**. When you remove an SBC that's associated with a voice route, you can choose a different SBC for the route on the **Voice Routes** tab. The voice route without an SBC will be deleted. ## Define Caller ID Azure Communication Services direct routing supports advanced caller identity control for outbound calls. Caller ID override allows you to replace the caller ID for outbound calls that match a specific voice route with a configured value. When an override is defined, the specified caller ID is used for all matching calls. If no override value is configured, Azure Communication Services uses the caller ID provided at runtime when initiating the call. This capability helps ensure consistent caller identification across outbound scenarios and enables alignment with enterprise or regulatory requirements. [](../media/voice-routing/azure-communication-services-direct-routing-caller-id.png#lightbox) ## Set Privacy Header You can control identity disclosure by configuring the SIP Privacy header that Azure Communication Services applies to outbound calls sent to your Session Border Controller (SBC). This setting is applied uniformly to all outbound calls routed through the SBC and allows you to enforce privacy behavior at the routing layer. The supported values are: - **ID**: which requests that the caller’s identity be withheld from the remote party, - **None**: which indicates that no privacy is requested and the caller’s identity may be disclosed. ## Define Signaling Transfer Behavior In order to optimize call signaling paths, we are supporting a new transfer behaviour: Direct Transfer. When direct transfer is enabled, Azure Communication Services does not remain in the SIP signaling path after the call is successfully established. Instead, ACS sends a SIP REFER to the remote endpoint, with the Refer‑To URI pointing to your SBC. As a result, subsequent SIP signaling occurs directly between the endpoints without passing through Azure Communication Services. This behavior reduces signaling hops and allows the SBC to manage the call end‑to‑end after setup. [](../media/voice-routing/azure-communication-services-direct-routing-settings.png#lightbox)