You will not have clear title to the rights. Book Packager A book packager takes on the risk of producing a book. It will offer the work to various publishers at a 'fixed' price. The publisher is guaranteed receiving a completed, printed book. Although the book is produced by the packager, the book will appear to be a regular title from the publisher.
Few authors are able to market an unsolicited manuscript through a book packager.
However, you are, usually, the publisher with your own ISBN and ownership of all rights to the book. There are also co-publishing arrangements. Sometimes a particular title is not attractive to a small publisher, yet the work has merit and could be successfully marketed. Or, the small publisher is interested in the title, but is unable to afford to make the investment in the work. In a typical co-publishing arrangement, the author may pay for some or all of the production and printing expense and will take title to most or all of the inventory.