Who usually do many calls iPhone (or any mobile device) always has its habits: some like to always do it with a headset, others prefer to connect the device to an external device for the connection and some others almost always use the speakerphoneto avoid touching your smartphone to your ear.
In any of these cases, you need to do a little action at the beginning of the call to set the audio the way you want by default, the iPhone will direct your contact's voice to the earpiece or the Bluetooth device that is connected to it. But did you know that there is a configuration, in the accessibility settings of the device, that allows the user to define exactly where he wants to receive the call at all times?
It is quite easy to make this change. Just go to iPhone Settings and then General Accessibility, touch the option ?Call audio?. There, you will see that the option selected by default is "Automatic" which is precisely the behavior that directs the call to the earpiece or the Bluetooth device. By changing the option to ?Speaker?, iPhone will always receive / make calls in speakerphone mode. By selecting the ?Bluetooth Headset? option, the wireless device will always be prioritized.
This tip applies to both regular phone calls and FaceTime audio calls. If you are a regular iPhone speaker, it is worth taking a look at these Settings after all, every half second that you save by pressing the ?speakerphone? button counts, doesn't it? ?