This is strange... I think it started after the latest upgrade.
Using Call Back... dialing from the keypad works fine. Calling from a Contact or Favorites brings up the dialog for which number to call back on, and selecting any of them just makes the dialog disappear with no call.
Switching to Direct Outbound, it works but the outbound number is using a 347 area code when I'm in the 518 one. It used to use a 518 one.
Anyone else having trouble? I'm a 3GS with iOS4 on WiFi.