[yann63]

Yes, Paris mobile network in subway is now pretty good. My second job was to install BTS for FTM (now Orange) in Paris including the subway in... 2000 ;-)

And we had to do it cooperatively with competitive carriers because of the lack of space in the tubes.

[w-m]

My experience (with the carrier “Free”) is quite different. If there’s data at all, it’s mostly Edge and will cut out when the train gets to the next station. In some deeper lines I won’t even get a phone signal.