Rakuten Mobile turned on commercial 4G service after a six-month delay, to become the fourth mobile operator in Japan, a move it claimed made it the first operator with a live service based on fully virtualised infrastructure.

The operator today (8 April) began offering 4G access under a tariff dubbed Un-Limit 2.0 plan, a JPY2,980 ($27.38) per month plan offering unlimited data when using its network, but with a 5GB cap when roaming on partner KDDI’s network (up from the original 2GB announced last month).

In a statement, chairman and CEO Mickey Mikitani (pictured) said with the combined strengths of Rakuten Group’s ecosystem and membership, “we aim to provide our customers with a mobile service unmatched by any other”.

The operator said its launch was the world’s first large-scale deployment using a fully virtualised mobile network, resulting in substantial reductions of capex and opex.

Rakuten Mobile unveiled its tariff plans on 3 March, and today emphasised it stood by an aggressive strategy of offering free service over the first 12 months for the first 3 million customers to sign up.

Despite the fanfare, Rakuten Mobile’s launch comes six months later than its original October 2019 target, with the operator at the time citing a shortage of construction personnel caused by preparations for the now delayed summer Olympic Games (which were due to take place in Tokyo this year).

It did, though, initiate a trial service using the infrastructure already available, gradually expanding its network in preparation for today’s launch.

However, while it claimed a “full-scale commercial launch”, its network coverage is currently limited to specific areas of just three cities: Tokyo, Nagoya and Osaka.

Outside those areas it must rely on KDDI’s network, as part of a roaming deal with the company.

The newcomer was scheduled to have 4,400 base stations up and running for the official launch, but offered no details on this in its announcement.

It also noted there may be some teething problems due to Covid-19 (coronavirus), with “a number” of its stores temporarily closed on 2 April as part of measures to prevent the spread of the virus.