United Mobile provides SIM cards for mobile phones. The cards allow you to call or make mobile data connections cheaply, anywhere in the world from your cell phone. The company's secret sauce is deals with more than 300 partners worldwide, so its users can roam across these partner networks at low rates.
Zurich, Switzerland-based United Mobile says its service is especially useful for Americans who travel abroad. If you exchange your standard SIM card for a UM SIM card, you can make and receive calls using your phone for up to 80 percent less than you would be otherwise charged by your US carrier, it claims.
SIM stands for Subscriber Identity Module, and a SIM card is a removable chip that contains personal data about you, such as your address book, and allows a carrier to match your identity with the mobile phone you're using. It comes with GSM-standard phones.
The least expensive chip costs $29, with more expensive options. The company uses uses seven different calling tariff-zones. Whichever zone you’re in, you a flat rate for incoming calls and a flat rate for outgoing calls.
Check out the US pricing charts pdf for more.
United Mobile has raised $15 million from Accel Partners. Previous investors include angels Morten Lund, one of Skype’s founding investors, Thomas Geitner, the former global chief technology officer of Vodafone, and Robert Zacconi, CEO of King.com.