SIPCoin: A Cryptocurrency for Preventing RoboCalling on the PSTN

Document Type Expired Internet-Draft (individual)
Last updated 2018-09-03 (latest revision 2018-03-02)
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Robocalling has become an increasing problem in the Public Switched Telephone Network (PSTN). While techniques like verified caller ID can help reduce its impact, ultimately robocalling will continue until economically it is no longer viable. This document proposes a new type of cryptocurrency, called SIPCoin, which is used to create a tax - in the form of computation - that must be paid before placing an inter-domain call on the SIP-based public telephone network. SIPCoin maintains complete anonymity of calls, is non-transferable between users avoiding its usage as an exchangeable currency, causes minimal increase call setup delays, and makes use of traditional certificate authority trust chains to validate proofs of work. SIPCoin is best used in concert with whitelist based techniques to minimize costs on known valid callers.


Jonathan Rosenberg (
Cullen Jennings (

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)