There are 3 options to upgrade.

Option 1: Two step Method using an SD-card or USB-memory-stick.

1. Plug in an SD-card or USB-stick with at least 2GB free memory (or enter an external SD card). Then start the Maxwell-10 WEB-UI and (klick on the Web Server Address - shown in the Maxwell 10 under "Settings=>WebUI - log in (Standard Password is "admin") and follow exactly the following 3 steps:
2. In the web-interface go to: System - Firmware Update page and check if the Data server field is (default) profile.gigaset.net/device
   
3. Press "Save"
4. Press "Update firmware"

 The update will be done in 2 steps.

1. Upgrade to new Jelly Bean software with USB drivers upgrade to support the USB memory extension.
2. Upgrade to Lollipop.

Option 2: One step method using external SD-card.

1. Enter an external SD-card (or plug in an USB-stick).
2. Download the software via the "Download" button on this page.
3. Unpack the zip file. You will get a .txt file with the Open Source License text and an encrypted zip file which is your firmware image.
4. In the web-interface go to: System - Firmware Update page and select the above extracted zip file.
   
5. Start the upgrade.

Option 3: One step method without external SD-card.

1. Do a factory reset of the Maxwell 10 to free all memory for firmware update.
2. Download the software via the "Download" button on this page.
3. Unpack the zip file. You will get a .txt file with the Open Source License text and an encrypted zip file which is your firmware image.
4. In the web-interface go to: System - Firmware Update page and select the above extracted zip file.
   
5. Start the upgrade.