How do I pair iPhone 3G, 3GS or iPod Touch Gen2 with Bluetooth device?
Tuner2 | Support | How-to Manual

With OS 3.0 or later, iPhone 3G, 3GS or iPod Touch 2nd generation can be paired with a Bluetooth output device such as stereo headsets or audio receivers. This allows Tuner2 to output audio direcctly to the paired Bluethooth device.

First, pair your iPhone 3G, 3GS or iPod Touch Gen2 with the Bluetooth device by touching on "Settings" from home screen.

In "Settings", touch on "General".

In "General", touch on "Bluetooth".

Switch "Bluetooth" on. Now your iPhone 3G, 3GS or iPod Touch Gen2 is in a discoverable mode. Turn your stereo Bluetooth device in a discoverable mode as well. (Consult your stereo Bluetooth user manual.)

Your stereo Bluetooth device should show up in your iPhone 3G, 3GS or iPod Touch Gen2 and paired. If not automatically paired, touch on the Bluetooth device to pair. In this case, our stereo Bluetooth device is Sony HWS-BTA2W.

Generally, stereo Bluetooth devices are not locked with passcode. If it is, enter it. If you don't know, look for the passcode in your Bluetooth device user manual. Otherwise, try 0000 (zero, zero, zero, zero).