Bluetooth backward compatibility

[wpcoe]

I have a Jabra Play wireless headset device that I bought in August 2013 which is Bluetooth 3.0. It works fine with my iPhone 4 which has BT2.1. However, it does not work (is not found by) my iPhone SE which is BT 4.2.

From what I've read on google searches Bluetooth is supposed to be backward compatible, like USB. i.e. You can plug in a USB3 device into a USB2 port and it will operate, but within the restrictions of USB speed/power/etc.

e.g. "Bluetooth 4.0 is backward-compatible with all other versions of Bluetooth, so you can pair existing Bluetooth headsets with the new iPhone without a problem." (In the context of an iPhone 4S which was BT4)

source: http://www.cnet.com/news/bluetooth-4-0-what-is-it-and-does-it-matter

Is there some setting for the iPhone SE (iOS 9.3.3) that will enable it to work with the BT3 Jabra Play?