This was a challenge as I have a ip6000 that I wanted the firmware upgraded.The information and solution is posted through out the forum but hard to grasp. There are a few key factors that one must understand initially to make the process easier.
Here's what you need to know
There are firmware upgrades(change) and there are firmware updates. When you go from 3.X to 4.X that is a firmware change. The whole dynamic of the system changed. Everything gets blown out. You will see the file system get reformatted and you lose everything. This is a special circumstance that requires an extra step not performed on Polycom's public server. The (UCS) Unified Communications Software which provides a new simple-to-use interface must be added. When you use the Polycom Server it gives you just the firmware which leaves the app missing hense "polycom error application is not present".
To remedy this you need to create your own provisioning server. Load all the firmware files along with the Updater and Upgrader.
Just as a pc will look at the USB port or CD Rom before it boots the Polycom phone will look in the
Provisioning setup. When you load those values then the phone will run its boot program to get the new firmware. Normally the values are the Polycom servers id.
Because you have to upgrade everything you need to point the boot program to your provisioning server.
The objective here is to have a place that the phone can get and load all the files it needs. This can be a laptop where you unzipped these three files.
put then in the same directory and make it accessable to the ftp server. The FTP server is a service feature you can turn on in Windows. (Google FTP windows 10). You will make a new user account with the phones name, give it a password. Now your laptop or PC will allow the phone to access the files. Make sure that the same info (user name and password matches the phone and PC. The phone will log into the laptop/pc and pull the files. It will upgrade the firmware and load the new app by itself.
Just as Steffen said over and over and over again. lol.
Hope this help