The present application provides an authentication scheme that allows a device to provide additional authentication of a Publicly Switched Telephone Network (PSTN) identity assertion made in a PSTN call by also sending an Internet Protocol (IP) communication. The device sends the IP communication generally in parallel with the PSTN call. The IP communication includes a network identity assertion, which optionally may be authenticated using a cryptographically secure technique. The network identity assertion, being more difficult to falsify, provides additional authentication of the PSTN identity assertion.