VoIP Phone Networks (Windows Embedded CE 6.0)

  • Article

1/5/2010

The network topology for an IP network that supports Voice over IP (VoIP) phones can vary greatly. This topic outlines a simple network that supports and enables testing of the VoIP phone functionality in the Windows Embedded CE 6.0 IP Phone design template. It does not necessarily represent the most efficient or best network design for your specific needs.

The following diagram shows the organization of this VoIP phone network.

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This network supports the following high-level functions:

  • Initiating and receiving phone calls on VoIP phones internal to the network. The phones use the SIP proxy server for call control and communicate directly with each other for media transport, via the Real-time Transport Protocol (RTP). Phones can also send SIP messages directly to each other by using the recipient's IP address or machine name in the phone number/address field. When phones send SIP messages directly to each other, both SIP and RTP content travels directly between the phones involved in the conversation.
  • Initiating and receiving phone calls on VoIP phones on the internal network, and PSTN phones. The VoIP/PSTN gateway appears to the SIP proxy server and VoIP phones as the IP endpoint. Similarly, the gateway appears to the external PSTN network as the analog phone endpoint. Internally, the gateway translates between SIP and PSTN signaling and media transport, and maps to the appropriate endpoints on both sides of the gateway. Because the VoIP phones consider the gateway to be the endpoint with which they are communicating, the RTP conversation happens between the VoIP phone and the gateway.
  • Retrieval of contact, address list, and free/busy information from an Exchange server. VoIP phones use the Windows Embedded CE Exchange Client Catalog item to connect directly to the Exchange server by means of the server's Exchange Outlook Web Access interface.
  • Presence registration and buddy list retrieval using a Microsoft Live Communications Server (LCS) machine. VoIP phones connect directly to the Live Communications Server machine using the Windows Embedded CE Real-time Communications (RTC) Client API Catalog item. For more information about Microsoft Live Communication Server, see this Microsoft Web site.
  • Authentication and provisioning with an Active Directory and domain controller machine. VoIP phones are network devices on the same network as the Active Directory/domain controller; therefore, authentication and provisioning happen like it would with any device.

See Also

Concepts

VoIP Phone Architecture