A self-forming VoIP connection capability is described that may be superimposed over wired networks, wireless networks, or combinations thereof. As described herein, a local network cluster forms while isolated from a conventional SIP server, or alternately may exist as a cluster of network nodes and clients that later becomes isolated from a conventional SIP server by a break in the network. Either way, each network node thus enabled with distributed SIP registry functionality according to this invention independently constructs a local SIP registry and SIP server capability within that node. Subsequently, while isolated from a conventional SIP server, VoIP conversations among client devices connected to nodes within an isolated cluster will continue, and nodes and clients may join or leave an isolated cluster with conversations able to be initiated or continued while a node has network connectivity to the cluster.