How does Apple dictation work?

Apple dictation works by converting your speech to text with a model that runs on the iPhone itself for supported languages. Tap the microphone on the keyboard, talk, and words appear in the text field, with automatic punctuation added as you go.

When you enable Dictation, the phone downloads a speech model, which is why it keeps working in airplane mode and why Apple can offer it free without time limits. You can even type and dictate at the same time; the keyboard stays live.

An iPhone can absolutely be used for serious dictation. Its ceiling is cleanup: fillers and formatting are left to you, which is fine for texts and limiting for real writing.

WriteVoice raises that ceiling; see voice to text for iPhone.