[Swansea Hackspace] IP Networking query

[Sharon Mitchell]

Hi All,

Could somebody ELI5 the following:

I have a Google Play Music sub, one of the features is 'Radio' where
you seed it a track and it streams similar genre.

In the settings I have told it to Stream and D/Load over wifi only - to
stop it gobbling All The Data.

However, when I walk to Uplands from Brynmill (so way out of range of
home wifi) I get an uninterrupted stream of radio (i.e. tracks that are
not local to my device).

Checking my device shows wifi connected not Data Plan.

How does this work.?
Is there some kind of 'back channel' talk going on between device and
somebody else's wifi.?

As an aside, it gives me confidence in my Spark.io project which relies
heavily on Cloud connection but cannot navigate captive portals, or as
some coffee-shop folk call them, 'Free Wifi'.

Sharon