My response from HTC:
I can understand how important it is to be able to connect your Sprint Touch Pro2 to your Bluetooth car kit. I would like to first begin by informing you that our HTC devices do not support all Bluetooth headsets. Compatibility alone does not guarantee perfect operation: issues like an unknown PIN code, unusual Bluetooth settings, signal interference, and other factors may still require your attention when using your HTC device with the Bluetooth product. We strongly encourage you to read over the User Manual of both your device and your Bluetooth accessory to fully understand how they are supposed to operate. I would recommend that you attempt to connect your device to another Bluetooth device to see if you are experiencing the same problems, I have attached a document of the Bluetooth devices we have tested. I would also like to make the recommendation that when you connect your phone to your car kit, that you then slide over to settings tab, select all settings, tap on the connections tab and in here I would like to make sure that the hands free setting is enabled on your phone, you can check this by tapping on the Bluetooth device’s partnership and then making sure that hands free is checked on and saved. I would also recommend trying to tap and hold on the Bluetooth device and setting it as hands free. I want to apologize for any inconveniences you may have experienced. I want to thank you for contacting HTC. In order to help improve our service I’d like to invite you to take a survey at
http://survey.htc.com/worldwide.
What a joke... I'm pretty sure having to press the end button multiple times is not how it is "supposed to work."