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Outside Voice Control Architecture

Microsoft Office Communications Server 2007 and Microsoft Office Communications Server 2007 R2 will reach end of support on January 9, 2018. To stay supported, you will need to upgrade. For more information, see Resources to help you upgrade your Office 2007 servers and clients.

Outside Voice Control acts as an intermediary to connect mobile devices and unified communications endpoints. Users with one of the following mobile devices can send and receive calls as if their phones were part of the enterprise network instead of cellular carrier network:

  • 2007 R2 version of Microsoft Office Communicator Mobile for Windows Mobile

  • Microsoft Office Communicator Mobile for Java (a client built on the Java Platform Micro Edition for mobile devices that are not Smartphones)

When a user makes a call from a supported mobile client to an enterprise peer, Outside Voice Control sets up the call as summarized in the following steps:

  1. The mobile client uses a data signaling channel to inform Outside Voice Control of the outbound call.

  2. Outside Voice Control initiates a request to the Mediation Server and PSTN gateway to establish a call to the mobile client using the mobile client’s cellular network.

  3. A cellular call is established with the mobile client. This is the first call leg.

  4. Outside Voice Control establishes a second call leg with the home pool of the enterprise peer that is the recipient of the call.

  5. A Front End Server in the recipient’s home pool looks up the recipient’s registered endpoints, and then it forks the call to all the recipient’s endpoints, including mobile devices.

  6. The second call leg is established with the endpoint that answers the call.

  7. Outside Voice Control provides call management to bridge the two call legs between the mobile client and the enterprise peer. Media flows between the mobile client and the enterprise peer through the Mediation Server.

Figure 1. Outside Voice Control architecture

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When an enterprise user or a phone user makes a call to a supported mobile client using one-number calling, Outside Voice Control sets up the call as summarized in the following steps:

  1. If the call originates from an enterprise peer, the call connects directly to Office Communications Server. If the call originates from the PSTN, the call connects to the Mediation Server, and then it connects to Office Communications Server.

  2. A Front End Server in the recipient’s home pool looks up the recipient’s registered endpoints, and then it forks the call to all the recipient’s endpoints, including the user’s cell phone, if it is running a supported mobile client.

  3. When the request to establish a signaling channel reaches the supported mobile client, the mobile client can determine that the incoming session is an audio call.

  4. The mobile client uses a data signaling channel to inform Outside Voice Control of the incoming call.

  5. The mobile client signals Office Communications Server to reroute the original signaling request to Outside Voice Control. Outside Voice Control initiates a request to a Mediation Server and PSTN gateway to establish a call to the mobile client’s cellular network.

  6. When the user answers the call on the mobile client device, Outside Voice Control and Office Communications Server connect the Mediation Server call leg with the originating call leg. Media flows directly between the Mediation Server and the caller.

  7. Outside Voice Control remains in the signaling path to provide call management until the call is terminated.