This functionality is supported through LNS on BB-ISA. LNS MLPPPoX can be used then as a workaround for PTA deployments, whereby LAC and LNS can be run back-to-back in the same system (connected by an external loop or a VSM2 module), and therefore locally terminate PPP sessions.
MLPPPoX can:
Increase bandwidth in the last mile by bundling multiple links together.
LFI/reassembly over a single MLPPPoX capable link (plain PPP does not support LFI).