@BarryS, welcome to PM. Calls are always made over the 3G network so you'll always see the LTE disappear when you're receiving or making a call. Technically this doesn't really effect your service. I think maybe the reason you had more bars with Rogers is because they're kind of the king in Toronto/Ontario, so they'll have more cell towers, while Telus (the parent company of PM) is kind of the king of the Western region (i.e. BC, Alberta). Not that this is an excuse but it is somewhat the truth. Although telus has built up their infrastructure greatly in Ontario, but sometimes you'll still get better vertical reception with Rogers more than the other carriers just because they've pretty much been developing their infrastructure here in Toronto the longest.
There was a story when Ted Rogers was alive, he was trying to make a call in his elevator at his head office (Mount Pleasant & Bloor), and he had no signal. He was so mad he had technicians stop everything they were doing and told them to make sure no matter where he is in the building he will always have a signal. So they installed a crazy amount of additional towers all over the building, and even underground. So if you have rogers and you're anywhere around Mount Pleasant and Bloor, you'll have 5 bars practically all the time.
