You must have the "+" at the start of the number and include country code. For U.S. numbers, the form should be: +15558675309 Where 1 is the country code, 555 is the area code, and 8675309 is the number. Without the "+", Skype won't work and say "incorrect address". You can edit your contact list to include the "+". When editing the contact phone number, just press the "s" key for a plus sign. You don't need to hold down the blue/green arrow key while pressing the "s" key. This has been reported as a bug. Hopefully a fix will be issued because it is hard to figure out what is wrong otherwise.