Alongside the introduction of iOS 10.1 and watchOS 3.1, Apple has switched on support for Apple Pay in Japan. This makes the iPhone 7 and Apple Watch Series 2 compatible with the FeliCa contactless payment system used by almost two million payment terminals in the country.

Supporting Apple Pay in Japan was not a trivial undertaking for Apple. Although FeliCa is an NFC-based contactless payment system, it’s not compatible with the systems used in most other countries. Apple had to equip Japanese devices with a different NFC chip to support FeliCa – also used in Hong Kong and Singapore – which is bad news for the rest of us when travelling to the region …

To use FeliCa, you not only need either an iPhone 7 or an Apple Watch Series 2, but it also needs to be a Japanese model: devices sold in the U.S. and elsewhere are not compatible. Locals will be able to use Apple Pay at any terminal supporting Suica, QUICPay, or iD. Apple Insider says that Apple Pay will support Japanese cards from American Express, JCB, MasterCard, Aeon, Orico, Credit Saison, SoftBank, d Card, View Card, MUFG Card and more.

The move is good news for Apple: FeliCa is so well established in the region as a standard form of payment that Apple Pay take-up is likely to be rapid, with Apple’s tiny take from each transaction likely to add up to significant revenue. Last year, FeliCa transactions totalled $46B.

Today’s launch doesn’t appear to be getting off to the best of starts. Bloomberg reports that commuters have been struggling to register their FeliCa train passes – which double as payment cards – into the system.

East Japan Railway Co. said users are experiencing difficulties connecting to the Mobile Suica contactless payment system, after the rail operator servicing Tokyo metropolitan area began accepting Apple Pay today. The trouble started shortly after 9 a.m. in Tokyo. While JR said services were restored after a couple of hours, Apple’s page showing the status of various services showed that there were still some lingering disruptions.

The problems are being attributed to the high numbers of people attempting to register cards on Apple Pay, which one consultant said was a good sign.

“It’s a shame that systems went down, but it shows just how much user interest there is,” said Eiichiro Yanagawa, a senior analyst for consulting firm Celent. “They’ll be able to learn from today’s experience to improve services for the future. We can probably take this as a positive sign,” he said.

Some consumers seem less convinced.

“This makes me worried about system stability going forward,” @ltdexp_1002M posted on Twitter. “Seriously? This may be the first service outage ever for Suica?” said another user posting under @taturou.

Apple had not responded to Bloomberg’s request for comment at the time of writing, but card registration issues on launch day are not uncommon.

Tim Cook visited Japan recently, stating that he hoped Apple could be a catalyst for moving away from cash. Apple officially confirmed the service was coming to Japan as its iPhone 7 event last month.

Apple Pay went live in New Zealand earlier this month, with the rollout among U.S. banks continuing. New York commuters also saw Apple Pay support added to the MTA eTix app.