Patent ID: 8223755

Claim:
A system comprising: a memory; and a processor in communication with the memory, the memory including computer code executable with the processor, wherein the computer code is configured to: provide trust relationship information for a telephone number, the trust relationship information indicative of whether at least one node considers a target node as including or as being associated with a Voice-over-Internet-Protocol (VoIP) call agent for the telephone number based on a determination, at the at least one node, that at least one public switched telephone network (PSTN) call to the telephone number arrived at the VoIP call agent, the determination made in response to receipt, from the target node, of demonstrated knowledge of at least one attribute of the at least one PSTN call that demonstrates knowledge of the PSTN call; and determine a target trust relationship from a validating node to the target node based on the trust relationship information, wherein the target trust relationship indicates a level of trust the validating node has in the target node being associated with or including the VoIP call agent for the telephone number, wherein the validating node and the at least one node are in different respective administrative domains of a network.