Apple Watch LTE SMS/MMS Function
Hey,
So I’m wondering why I can’t receive any SMS/MMS (only iMessage) on my cellular Apple Watch when I’m out running and my phone is powered on and left at home? Although I can receive calls (and vice versa).
Question marked as
Use your Apple Watch without your iPhone nearby - Apple Support
1. To receive SMS, MMS, or push notifications from third-party apps on your cellular Apple Watch, your paired iPhone must be powered on and connected to Wi-Fi or cellular, but it doesn't need to be nearby. You also need to be signed in to iMessage on your iPhone.
SMS/MMS requires a cellular radio that can talk to the cellular voice network. The Apple Watch has just a cellular data radio that can only talk to the internet, and using VoIP for voice calling.
A full function cellular radio is too big, and consumes too much power.