I spoke with the guys at UM. The United-Mobile SIM is a re-branding of Riiing. As of Decmber 1 the rates and coverage are the same. Since last week, goiing to
www.riiing.com re-directs to www. united-mobile.com. You can recharge Riiing on that web site.
For the last 3 month the Riiing SIM card holder came with "Powered by United-Mobile" printed on it.