I how my Sound ID 510 bluetooth that was paired with iPhone 4
I had not attempted to use it my my 6 Plus, so I tried to pair it. My phone would not recognized it
I found the solution in post from Oct 2011:
Problem solves with a soft RESET of the SoundID unit.
Here is the way to reset the unit:
To RESET your headset: If you experience problems during pairing, you can perform a soft reset on your headset. Place the headset into pairing mode (e.g., Manual Pairing - press and hold Main Button for 3 seconds as you turn headset on) and wait for LED to flash red and green. Then tap the Main Button twice. The status light will turn ORANGE. Turn the headset OFF and then ON and it will go into pairing mode (e.g., LED will flash red and green). You must then re-pair the headset to your phone (e.g., in phone blue tooth menu).
It worked for me.
I had the application on the 6 Plus and the application works.
Tried looking for the app in the app store but it doesn't seem to be there so app was probably transferred with other apps when going from 4 to 6 Plus