[germanier]

Sorry, I edited my comment while you replied. O2 officially is at 80% LTE coverage according to the latest BNetzA report. But as far as I know they often use cells that can't handle the needed capacity.

When the networks where new, some offered roaming in some areas, I remember that as well. The E-Plus/O2 roaming was more of a technical thing when they merged, it should now be largely gone and a single network.

[mschuster91]

It's iirc their backhaul network that can't keep up, not the technology they use in their BTS. Telekom and Vodafone have large fiber networks (Telekom for DSL, Vodafone for cable-Internet) so they can use existing infrastructure (conduits, electricity lines, right-of-way for houses housing concentrators, routers etc) while O2/Eplus had to build out/rent everything.

In addition O2/Eplus historically got the cheaper but more inefficient frequency ranges which made them the "low cost" players.