As rumored, the ISIS mobile payment system will debut this coming Monday, October 22, after being delayed several times. Word comes from Jaymee Johnson, who is responsible for marketing the platform, so we know that this time it's official.Once the system goes live, a handful of AT&T, Verizon, and T-Mobile customers will be given the chance to enjoy spending their cash at select stores by tapping their smartphone onto a terminal at the cash register, instead of taking out their wallet. And by handful we mean those subscribers who have a compatible device running the ISIS mobile application, who have an ISIS-supporting SIM card, and happen to live in Austin or Salt Lake City. Wondering if your handset is on the list?Let's see: if you are a Verizon subscriber, the only smartphone that will work from day one is expected to be the HTC Droid Incredible 4G LTE . T-Mobile has three devices that should get along with ISIS well, namely the Samsung Galaxy S III Samsung Galaxy S II , and the Samsung Galaxy S Relay 4G . The most smartphones compatible with ISIS are on AT&T and those are the Samsung Galaxy S III LG Escape , and HTC One X . By the end of 2012, the total number of smartphones compatible with ISIS is expected to reach 20.That is all we know so far, but we are hoping to hear more details about ISIS on Monday, as soon as the system goes live. Is anyone thinking of giving it a shot next week? Let us know down in the comments!source: Engadget