According to a New York Times report on Tuesday, Skype has been unavailable on Apple’s Chinese App Store and on various Android app repositories for almost a month now.

Apple (AAPL) told the publication that it had been “notified by the Ministry of Public Security that a number of voice over internet protocol apps do not comply with local law,” so it had removed those apps in its Chinese store.

Android app stores run by local web giants such as Huawei and Xiaomi also don’t carry Skype anymore—Google (GOOGL) doesn’t run its Play Store in the country because of local laws, so Android users have to turn to third-party services such as these for their app downloads.

Microsoft (MSFT) told the Times that Skype’s removal from Apple’s App Store was only temporary, and it was “working to reinstate the app as soon as possible.”

It’s not clear which law Skype is breaking. It doesn’t provide end-to-end encryption, though it might be that the Chinese authorities don’t like its encryption of messages in transit between people’s computing devices and Skype’s servers. It’s also possible that Skype is falling foul of a recently introduced Chinese rule that demands the use of verified real names on online platforms.

China has recently been particularly restrictive of online speech, due to the high-stakes Communist Party meeting that took place last month. However, Skype’s disappearance from the app stores seems to have taken place after that event.

Apple took flak from digital rights activists earlier this year when it removed from its Chinese App Store apps that could be used to bypass state censorship in the country.