An e-commerce company switched on a national mobile network this week, in the middle of a pandemic that has most of the planet indoors, and the whole thing is virtualized Open RAN running on general-purpose servers. I did not expect the proof to arrive from Rakuten, and I really did not expect it to arrive now, with engineers commissioning cell sites while the rest of us are told not to leave the house.

Here is what Rakuten Mobile actually turned on. The radio access network is software. Altiostar’s open virtualized RAN runs the baseband in the cloud on ordinary servers, NEC supplies the radios, and there is no sealed base station bought whole from a single incumbent anywhere in the design. Tareq Amin, the engineer who architected it, has been saying for two years that a carrier could build this way, and Japan just became the place where he got to prove it on paying subscribers.

This is the moment the paperwork becomes real. Last year I wrote about the first Open Fronthaul specification and asked whether two vendors could actually interoperate on a live site or whether it would fall apart in the field, the way open telecom promises usually do. Rakuten is the answer carrying real traffic. The architecture five operators founded an alliance around is now somebody’s phone service, not a plugfest demo.

I want to be honest about how much easier Rakuten had it than the incumbents will. This is a greenfield. There was no legacy network to rip out, no twenty years of Ericsson and Nokia gear to keep alive while you swap it, and the whole thing sits in a dense country where fiber is cheap and everywhere. Rakuten is also a fourth entrant with everything to prove and nothing to protect, which is exactly the profile of a company willing to bet on unproven architecture. An operator with an existing national network and quarterly numbers to defend is playing a much harder game.

There is also a gap between switching a network on and running it reliably for a decade at scale, and I am not going to paper over it. Launch day is the optimistic day. The real test is whether virtualized Open RAN holds up under the boring, brutal load of millions of subscribers over years, and we do not have that data yet.

Discount it for the greenfield and the timing and it is still the most important thing that has happened in this story so far. The word people used for years was impossible, and impossible just went commercial in Japan. What I want to know now is whether anyone can do it without a blank slate, because I strongly suspect Rakuten already plans to sell this model to every operator that cannot build it themselves.

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