This app will connect to a Bluetooth speaker of your choice, then while you are talking, your voice will be streamed via your phone to the speaker. As it is a wireless connection, you can walk around with your phone while talking.

Once the app starts, it will look for nearby Bluetooth speakers and list on Connect Speaker tab. Select the speaker to connect/pair to, move to Talk tab and you are all set. While talking to your phone, your voice will streamed to the connected speaker. Tap on the microphone icon in Talk tab will switch from talk to mute mode or vice versa.