I meant the LTE network... which is exactly what you stated (band 4). I think the other two carriers support another LTE band (is it 7?)
Check this thread over at HF. I'm not sure how accurate the information is but it seems to me like LTE operates on more than just band 4.
"Telus uses Band 2 and 5 for HSPA and Bands 2, 4, 5, and 17 for LTE with Band 7, 13, and 29 coming on over the next few years"
What LTE freq is used for VoLTE as I am presently using it on my i6s with my traitor carrier! (Rogers)
lol for @Martin