2014 Mazda CX5, Samsung Galaxy S7 phone on ATT network. Bluetooth connects fine, and the phone works. Text messages get uploaded, but when I try to play the message, there is no sound.

SOURCE: bluetooth conection

you have to activate blue tooth connectivity on your phone

SOURCE: Windows Vista wont connect to these headphones

Try going to control panel->sounds->make the hands free audio the default.

SOURCE: Garmin 760 - No Voice Directions

Go back into your tools and settings and re select the voice of american jack and see if it comes back on.
I lost the voice 2 days ago while on a trip from tenn. to florida and this fixed it. we never shut off the voice but somehow while using bluetooth or FM trans it shut off voice transmiting.

SOURCE: motorola h710 bluetooth will connect to phone but no audio

I disabled the bluetooth from my phone. I then turned off my phone and rebooted it. Once the phone was turned back on, I paired it up with the bluetooth and then it worked. So disabling and removing everything and starting over worked.

SOURCE: Trying to connect my Samsung Wep180 bluetooth to my phone

Hold the WEP180 multifunction switch down (the big one on the top) until the light is constant blue (not falshing). You will then be able to find the device from anothe 'phone. Provide a pairing key of 0000 (four zeros to pair).

You will only have to do the above once. After the initial pairing you 'phone will find the WEP180 headset as soon as the blue light flashes.