After January 30 2013, Google dropped Exchange ActiveSync support.
Now if you add a Google account in Windows Phone 7.8, you can sync only emails.
But if I want to sync my Google Contacts and Calendars...??
Just follow this steps:
- Go in Settings >>> Email + Accounts.
- Add an account.
- Choose Outlook (Outlook.com, Exchange, Office 365).
- Write you Google email, password and press Sign In button.
Fill the new page with this informations:
- Account: your Google email
- Domain: google
- Server: m.google.com
Et voilà, you done! :)
