Thank you for your message.
Unfortunately, right now there's no address book sync feature in the mobile Viewer. However, we plan to significantly improve a mobile Viewer, namely, to implement a full-fledged address book that would be possible to sync with the desktop Viewer and with the RU Server as well. Unfortunately, we cannot provide any specific ETA on this yet. Sorry for the inconvenience.
Please let us know if you have more questions.