Google Calendar has Web, smartphone, and even desktop applications to help make managing your schedule an easy process. But if you don't want to fuss with any applications and just want to add a quick reminder to your Calendar, sending an SMS is the best method. There's a little bit of setup involved, but it's quick and painless.
Step 1: Log in to Google Calendar on the Web and go to the Settings menu in the top right corner (click the cog and then go to Settings).
Step 2: Go to the Mobile Setup tab in the Settings area, and enter the mobile number you will use to communicate with Google Calendar. You cannot use Google Voice at this time since it cannot communicate with short mobile codes.
Step 3: Enter the verification code that is sent to your phone, and then adjust when you want SMS notifications and for which calendar events.
Step 4: Add Google Calendar to your phone Contacts with the number 48368 (spells GVENT).
Step 5: Send an SMS to Google Calendar with the event you want to create. Make sure this is sent to the short code 48368 and not the standard phone number that Calendar used for the verification process.
Example: Pick up Allen 8:30pm today
You will receive an SMS that verifies the event was created (as shown above).
If you want to stop receiving SMS notifications at any time, just text STOP to the Google Calendar short code 48368.