I will arrive with Lufthansa from FRA and will go further wih Philippines Airlines to MNL. The eticket I have already, but the boarding pass for MNL I suppose I will get in T3. A terminal bus is connecting T3 with T2

Big question for me now:
do I need to go through the immigration to access the bus, or can I use the bus service just as an international transfer passenger without any immigration and visa procedure ?

best regards
miloe