Looking here: http://www.4g.co.uk/bt-4g-coverage-network-summary/
Says BT Mobile does use 4G on 800Mhz, however I asked on BT's live chat and was told know. Does anyone know for sure?
To use EE's 800mhz you have to be using VoLTE, and currently only EE contract accounts (including SIM only contracts) can use VoLTE.
BT mobile and Plusnet mobile whom are both virtual networks (MVNO) on EE are both NOT supplying VoLTE services.
(Not many phones support VoLTE, iPhones from 6, and SOME androids with EE's firmware).
plusnet unlimited fibre
80/20 since 2 Jun 14 - Sync as of 5th Feb 17: 57,821/9,173 kbps with G.INP
18 years of UK broadband since 1999 ntl:cable modem trial -Router: Asus RT-AC68U with HG612 - BQM