The trial will launch in March 2020, providing 4G connectivity on platforms and even in tunnels between Canning Town and Westminster on the Jubilee line (including passenger walkways, ticket hall, etc).
The trialling of 2G, 3G and 4G mobile services along this section of the London Underground network will allow TfL and the mobile operators to gain valuable experience of delivering mobile services on the Underground ahead of awarding a concession to deliver mobile coverage across the whole Underground network. The next stage of procurement for the concessionaire will begin shortly, with a look to award the contract by Summer 2020.
I think this is progress !!! Certainly internet connectivity is a move forward. Not so sure about voice calls. We have enough people speaking (loudly) into their phones on buses, it won't be a good move to have this on tube trains, particularly given how loud some will speak due to the train noise.
As for having 4G in station passages, that could be 'interesting' when people pay more attention to their phones and not enough attention to what is happening around them.