No, there are no special attributes, but it's recommended to check it. Use a phone from your phone and then export it to your computer in CSV file. This way you will see exactly what's the CSV file format you need to define, then make proper adjustments to your contacts file and upload it again. Additionally, if you have a smartphone with Android, for example, it's possible that the contact list was installed correctly, but it's set up to be hidden. In this case access Contacts > Menu button > Display > All.