Isis is gearing up to expand its Mobile Wallet service nationwide in the coming months, but its plans don't end there. The company has just announced that it's teaming up with American Express to bring the latter's Serve platform to Isis Mobile Wallet. Serve account holders will be able to make use of most of the features they already expect from Amex, like loading cash to their accounts, paying bills electronically and adding funds via direct deposit. By joining up with Isis, Serve is now unlocking the Mobile Wallet's capabilities, like NFC-powered payments at participating retail locations. Though Isis is currently limited to Austin and Salt Lake City, the company -- now with Amex on its side -- hopes to reach customers coast to coast before the year is out, though we don't have a specific date for availability just yet. For more info, check out the press release after the break.