That is a number to the RF.com Media Server. From your iPhone on AT&T within the United States, for example, that is a local call (yes, the 415 area code in San Francisco is local to the rest of the country to the iPhone).

Here's what's happening when you use RF Dial.

You dial a number on that spiffy orange web-based dialer of ours. That number, as well as your RF Dial user ID,  your password, and the service chosen in the dialer pulldown menu, is sent via the Internet (WiFi if you're connected, Edge/3G if not, but it should be quite quick regardless),  to the RF.com Media Server. Our server then sends back a bit of HTML code that tells the mobile phone it wants to make a call. The mobile phone wants you to approve that call . . . and that's a good thing, or else any rogue web page out there can force your phone to make a call without your knowledge. When you approve the call to us, our server uses your caller ID to learn who you are, and then completes the call you are trying to make based on the information it first received from you.