Trick to make all incoming calls to your iPhone come through Speaker-phone by default
Sometimes its better to use your iPhone’s speaker phone when answering calls, specially if you are driving and will like to focus your attention to driving.
Apple has provided a method for this to work, partially as we will see, this tip comes from RedmonPie.
In order to get started please go to Settings -> General -> Accessibility.
Below is how enable the speaker phone for all incoming calls on your iPhone by default: