This package flashes software to your phone.
5.9.3.2857
https://support.polycom.com/content/dam/polycom-support/products/voice/business-media-phones/release-notes/en/uc-software-release-notes-5-9-3.pdf
https://documents.polycom.com/bundle/ucs-ag-5-9-0/page/c-ucs-ag-product-overview.html