On the piccadilly line around midday in the front car going north. We
waited a while for a train so unlikely anything was in front of us but
we stop between manor house and turnpike lane anyway. 2 minutes later
I hear the drivers door opening then 10 seconds later we're off with
no further stops in the tunnel. We get to turnpike and driver gets out
to use platform phone. Another 2 minutes we're off again to wood
green , yet again no stops , where the driver again gets out to use
the platform phone. After that it was a normal journey.

What was going on ?

B2003