When uploading a DNC file please make sure that the list has only one column and it only contains the numbers to be added and that it is in either CSV (Comma Delimited) or .XLS format.
Go to Phone system>DNC and click on Upload File
Click on the box that says Drop Files Here, select the file you want to upload and press Open.
Now click on upload and wait for the confirmation.
You can now click on close and check to make sure all the entries have been uploaded.