It allows to perform upload and download of contacts to the system. You can upload for update both already existing contacts, so as add the new ones. Just choose the parameters that correspond with your file and click on the upload button. You'll see the initial window, where you can configure the fields matching and continue with the upload itself. Once the upload is complete, you'll be able to review the information about the upload performed. To download the file, just filter required contacts and perform the download by the specified parameters.