Mobile phone coverage expanding on the Northern and Central lines

The next phase of expanding mobile phone coverage on the London Underground has been revealed, with more of the Northern and Central lines coming on first.
Projected phone coverage in tunnels – green is existing coverage (c) TfL
At the moment, along with the Jubilee line between Westminster and Canning Town, there is phone coverage in the Central line between Holland Park to Queensway and the Nothern line between Archway to Kentish Town.
According to a map included in TfL’s latest Ma