our new office block is coming up, and TM just told us they no longer provide any copper phone lines to new premise, all will be fiber VoIP based

since I'm kinda a VoIP noob, our contractor told us to get an IP PABX to connect to TM's SIP something like that, issit?

then I saw online there's something like cloud PBX? where no hardware required on premise?
means if I subscribe to the cloud PBX, i don't need the TM's SIP package anymore? or I still need but no longer need a PBX on premise?