... to Vonage, Broadvoice, or other VoIP providers, or to use with your own VOIP SIP PBX, such as Asterisk. This unit is ... high-resolution display. Part of Linksys Small Business IP Phone Series, the SPA921 IP Phone includes a high-resolution display, speakerphone, and ... a residence or business using a hosted IP telephony service, an IP PBX, or a large scale IP Centrex deployment. The SPA-921 leverages ...