(keitai-l) i-mode over GPRS operation mode

Technical question about i-mode_over_GPRS networks 'modus operandi':
does anybody know if i-mode terminals distributed in Europe (mostly from
NEC) open a PDP-context whenever they are switched on (under GPRS coverage,
of course), or do they perform just a GPRS network attach?
AFAIK, normal GPRS terminals usually perform just an attach (less
resource-consuming), however this may vary terminal by terminal.

Thanks
Giorgio