Call them and wait for them to answer
Speak clearly and calmly
Say their name first
Ask if they are awake
If they do not respond, repeat their name louder
Tell them to get up now
Mention the reason they need to wake up
Keep your message short and direct
Pause between sentences so they can respond
If needed, call again after a few minutes
If they are hard to wake, contact someone nearby who can check on them