How to use external microphone for phone calls?

Connected to iPhone via lighting port the external microphone gets picked up by Apple’s apps like VocieMemo, GarageBand, iMovie - no magic needed.

However, when it comes to making phone calls - it gets very frustrating. External microphones connected via headphones jack are fine. All of them. Bluetooth devices - no problem.

Why it’s “impossible” to use external microphone connected via lighting port for the phone calls?

I refuse to believe this.