Question about Xiaomi 13 Ultra

13 Ultra, 256GB, 12GB RAM,
Web 23. Okt. 2023 · XIAOMI 13 Ultra, 512GB, 12GB RAM, Betriebssystem: Google Android 13 • GSM Quadband, LTE Advanced Pro, 5G SA, 5G NSA

Hi,
this is the international version of the phone, it will work in the following 4G Bands:
1, 2, 3, 4, 5, 7, 8, 18, 19, 20, 26, 28, 38, 40, 41, 66

You can find the corresponding frequencies for each bands here:
en.wikipedia.org/wiki/LTE_frequency_bands

I am not sure a single band 20 to 800 MHZ as per your question actually exist as such
I believe that range is likely covered by multiple bands
(but I am not an expert on the topic)

I hope this helps

Best
Massimo

very perfect hendy