Here are some steps where you can make your appointments in Google Calendar and get those as remainders in your mobile.
1. Login in to your Gmail
2. Click the Calendar link
3. Click Settings (this is the setting for Calendar) to get the Calendar Settings page
4. Click Mobile Setup link
5. From the Mobile Setup page, enter your mobile phone number and click “Send Verification Code” button.
6. Once you click “Send Verification Code” button you will get a verification code by SMS.
7. Enter the verification code here and click “Finish setup” button
8. Click save button.
9. To test how it works, create an event.
10. Edit the event
11. You can see from the options menu an item called “SMS” select this option and click save.
12. You will get an SMS according to the time what you have mentioned at the time of creation of the event. This can be set whether you want to get the SMS alert before xx minutes, hours, days and weeks.
This alert can also be generated as an email alert or a pop-up (in Gtalk).