Call Forwarding

Automatically redirect incoming calls from your DID number to another destination using local in-country routing. Forwarded calls are delivered through your configured Outbound Trunk, with diversion routing enabled to preserve the original caller and DID information, ensuring callers can still reach you even when your primary device or platform is unavailable.

Call details are preserved through SIP Diversion header, which maintain the original caller ID, the dialed number, and related attribution information when forwarding through the outbound trunk.

Note

Call forwarding uses local routes to deliver calls within the same country using domestic networks. For this reason, it is supported only for local calls. Learn more here: Outbound Dialing.


Diversion Routing

Diversion Routing is a SIP-based mechanism used to redirect inbound calls to another destination by including the SIP Diversion header in the signaling. This header carries the originally dialed DID and caller identity, allowing forwarded calls to be routed through local in-country paths while preserving full call information. The mechanism enables reliable local forwarding, call tracking, and accurate presentation of the original caller ID.


Requirements

Important

To enable Diversion Routing on your Outbound Trunk, please request activation of the Diversion service by contacting DIDWW Technical Support at support@didww.com .


Diversion Call Flow

The sequence below outlines how Diversion Routing processes a forwarded call.

  1. An inbound call arrives on your DID.

  2. A SIP INVITE is sent to your equipment (PBX or SBC) including a Diversion header with the originally called DID. Example: Diversion: <sip:+18001234567@sip.didww.com>;reason=unconditional

  3. Your PBX or SBC forwards the call to another destination using your Outbound Trunk, preserving or reinserting the Diversion header in the INVITE sent to the DIDWW outbound signaling endpoint.

  4. The Diversion header is validated to ensure that the DID in the header belongs to your account.

  5. The call is routed via a local in-country termination partner, completing the call while keeping the original caller ID and DID attribution intact.

Note

Forwarded calls should be sent only through an Outbound Trunk with the Diversion service enabled.

Call Flow Diagram
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sequenceDiagram
    autonumber
    participant C as Caller
    participant DIn as DIDWW Inbound SIP Trunk
    participant PBX as Your System PBX / SBC
    participant DOut as DIDWW Outbound Trunk
    participant P as PSTN Destination

    C->>DIn: INVITE to DID (+18001234567)
    DIn->>PBX: INVITE with Diversion header
    PBX->>DOut: INVITE to forwarded number (Diversion preserved)
    DOut->>DOut: Validate Diversion header (DID on account)
    DOut->>P: Route call
    P-->>C: 200 OK / RTP (CLI and DID preserved)
Use Cases

  • Unconditional Forwarding (CFU) – Forward all calls immediately to another destination (e.g., voicemail or mobile), preserving the original DID and diversion reason.

  • Call Forward on Busy (CFB) – Redirect callers to another endpoint when the primary device is busy.

  • Call Forward on No-Answer (CFNA) – Divert calls after a timeout period while keeping the original caller ID and DID.

  • Call Forward on Unavailable (CFUNV) – Route calls to backup numbers when the endpoint is offline or unreachable.

  • Automatic Call Distribution (ACD) – Divert calls to queues or after-hours destinations while retaining the full diversion chain.

  • Voicemail – Deliver calls to voicemail systems with the correct diversion reason and original called number.

  • Call Tracking – Preserve campaign/source identifiers by maintaining the original DID in the Diversion header.


Supported Countries for Diversion Routing

Argentina

Australia

Austria

Belgium

Bosnia and Herzegovina

Brazil

Bulgaria

Canada

Czech Republic

Chile

Croatia

Denmark

Finland

France

Georgia

Germany [1]

Greece

Ireland

Israel

Italy

Latvia

Lithuania

Luxembourg

Malta

Mexico

Netherlands

New Zealand

Nigeria

Norway

Panama

Peru

Poland [2]

Portugal [3]

Serbia

Slovakia

South Africa

Spain

Sweden [1]

Switzerland [1]

Thailand [1]

United Kingdom

United States