Using PSTN Reachability to Verify VoIP Call Routing Information

Logic encoded in one or more tangible media for execution and when executed operable to;

• verify one or more Voice-over-Internet-Protocol (VoIP) call agents for respective destination telephone numbers based on demonstrated knowledge of previous public switched telephone network (PSTN) calls to the respective destination telephone numbers;
• receive a call initiation message identifying a destination telephone number;
• and
• conditionally initiate a call over a VoIP network to a target VoIP call agent, or over a circuit switched network, based on whether the target VoIP call agent has been verified for the destination telephone number identified in the call initiation message.

An apparatus, comprising

• one or more network interfaces;
• a memory;
• one or more processors;
• and
• a call agent application physically stored in the memory comprising computer-readable instructions operative to cause the one or more processors to:
• verify one or more Voice-over-Internet-Protocol (VoIP) call agents for respective destination telephone numbers based on demonstrated knowledge of previous public switched telephone network (PSTN) calls to the respective destination telephone numbers;
• receive a call initiation message identifying a destination telephone number;
• and
• conditionally initiate a call over a VoIP network to a target VoIP call agent, or over a circuit switched network, based on whether the target VoIP call agent has been verified for the destination telephone number identified in the call initiation message.