Comment by numpad0

Not home country, home PLMN(~=carrier). IIRC there were changes in 4G/LTE that lets the GW be at visiting carriers.

I'm suspecting that that post-4G architecture is just formalization of actual commercial deployment. Latency for roaming data was long inconsistent with the 3G diagrams, and exorbitant roaming fees that would be consistent with the diagrams also started rapidly subsiding from late 3G era.