The CSV upload is used for faster creation of user extensions. You can create hundreds of extensions by uploading just one .csv file with user data in it, rather than clicking hundreds of times on the 'Add new extension' button.

CSV stands for Comma Separated Value.

Create one file (e.g. exstension.csv) on your desktop and add the following lines to it:

John Smith,john@domain.com,1000

Joanna Cox,joanna@domain.com,1001

As you can see, these lines stand for: Full Name, Email, Extension Number.

When you upload this file to your PBXware, these two extensions (1000 and 1001) will be created. The provided names and emails are associated with the added extensions.