I feel that ISXPAY may be operational already. Just because the website isn't updated doesn't mean it is not in play. A look at the ISX site indicates a push for this service, along with their others.
ISXPAY.COM now diverts (after about 10 seconds) to the ISX website, where ISXPAY is heavily highlighted. https://www.isignthis.com/#
ISX Price at posting:
15.5¢ Sentiment: Buy Disclosure: Held