The name is the thing. The name of this Open Identity Exchange White Paper, the "ARPU of Identity”, is deliberate. ARPU, Average Revenue Per User, is one metric telcos use to measure success. By deliberately using a traditional lens that telcos use, this paper puts emerging Internet identity markets into a pragmatic perspective. The focus of the white paper is on how mobile network operators (MNOs) and other telcos can become more involved in the identity ecosystem and thereby improve their average revenue per user, or ARPU. This perspective continues OIX's “Economics of Identity” series, or as some call it the "how do we make money in identity” tour in the emerging Internet identity ecosystem. OIX commissioned a white paper reporting the first quantitative analysis of Internet identity market in the UK, where HMG Cabinet Office hosted workshops on the topic at KPMG's headquarters in London and at the University of Washington's Gates Center in Seattle. The timing of this paper on business interoperability is coincidental with work groups in the OpenID Foundation developing the open standards that MNOs and other telco players will use to ensure technical interoperability. GSMA's leadership with OIX on pilots in the UK Cabinet Office Identity Assurance Program and in the National Strategy on Trusted identity in Cyberspace offer opportunities to test both business and technical interoperability leveraging open standards built on OpenID Connect. The timing is the thing. The coincidence of white papers, workshops and pilots in the US, UK and Canada with leading MNOs provides a real-time opportunity for telcos to unlock their unique assets to increase ARPU and protect the security and privacy of their subscribers/citizen. In my OpenID Foundation blog, I referenced Crossing the Chasm, where Geoffrey A. Moore argues there is a chasm between future interoperability that technology experts build into standards and the pragmatic expectations of the early majority. OIX White Papers, workshops and pilots help build the technology tools and governance rules needed for the interoperability to successfully cross the "chasm." Several OIX White Papers speak to the "supply side" how MNOs and others can become Identity Providers (IDPs), Attribute or Signal Providers in Internet identity markets. Our next OIX White Paper borrows an industry meme (and T-Shirt) for its title, "There's No Party Like A Relying Party". That paper speaks to the demand side. Relying Parties, (RPs) like banks, retailers and others rely on identity attributes and account signals to better serve and secure customers and their accounts rely on technical, business and legal interoperability. By looking at the "flip sides" of supply and demand, OIX White Papers help us better understand the ARPU, the needs for privacy and security and the economics of identity. Don