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In the Switchvox scenario, you use a paging adapter as an endpoint for a SIP Phone extension. That way, a Switchvox user can dial the extension of the paging adapter to make an announcement, and the paging adapter handles the multicast transmission to some or all of the Digium Phones on a network segment. For instructions on creating a SIP Phone extension, see Create Phone or Virtual Extensions.
There a good selection of paging adapters with multicast support (e.g., CyberData, Valcom, Algo). From Switchvox's perspective, that device is just another SIP endpoint, so compatibility is straightforward.
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