Compatibility Nvoice Mobile (FMC) - iPhone Download The iPhone FMC client is also compatible with older iOS systems. However, functions may be limited with older software versions. We recommend using the FMC client with the latest iOS version. We can only provide support for official iOS software versions. We do not provide support for iPhones, which were unlocked without authorisation (so-called “jailbreak”). Therefore, please be sure to always operate your iPhone with the official iOS software.