We can use towers that are rated 4G but will never reach the 21.1 Mbps. I thought hspa+ was their high end 4G, and standard 4G was just hspa. I only say that because UTMS is 3G, not hspa.
MyTouch 3G (Yeah, I know...) Rooted w/ unlocked bootloader - Retired
G2 (Desire Z) Rooted w/ unlocked bootloader and carrier restriction - Retired
Epic 4G Touch (Galaxy S II) - Retired
Nexus 4 16GB - Rooted w/ unlocked bootloader - Retired
T - Mobile Galaxy S 4 - Knox Free. Running Wicked v10 w/ Chronic kernel - Current
24kbps 1080p w/ 320kbps audio @ 48KHz camera mod
by me. Also w/ How-to