Poly Edge E220 custom logo and background

In the official HP admin guide for the Edge series, download the file from the link below, then open and search for background. You'll want to add the parameters to a Zoom Phone template that will allow bulk background management to all devices. I generally go into my Poly e550's web interface and use a public facing website URL as my phones background, but that's my phone only. You will also have a logo option to setup and do the same, use the logo parameters with the same phone template. I would add a test template and play with your device only that way your not rebooting all devices as changes to ZP templates causes phones to restart. 

https://kaas.hpcloud.hp.com/pdf-public/pdf_9138333_en-US-1.pdf