It was noted on the blog that the Belkin TuneTalk Stereo works with an iPhone 3GS running OS 3.0.1. Is it known to work under OS 3.1.2?
Yes.
I'm considering trying a TuneTalk with SignalScope Pro, but would like some assurance that it will work before I purchase it.
It works fine. In fact, the TuneTalk is now the device I typically recommend.
Ben