Yes you can send SMS to any mobile number worldwide. You will just need to select the country codes that you use within the Admin section first so that the mobile number has the correct area code. Please note text costs vary worldwide.
1) Go to admin by clicking on your user name and icon. Select System Options from the dropdown.
2) Click on Mobile Countries.
3) Tick the countries required and press Save.
When adding a contact's mobile number, these additional country codes will appear in the dropdown.