Most operating systems (including mobile) offer support for Opus codec. Opus implementation is detailed in RFC 6716 (and RFC 8251 errata). Opus is the preferred (and mandatory) codec for web browser voice communication implementations described in WebRTC standard
Human speech Opus encoding is supported in the following web browsers:
Google Chrome (including Chromium)
Gstreamer-based Unix web browsers
Other uses of OPUS
Opus codec use cases are not limited only to web browsers. One of the most popular use of codec is its implementation in WhatsApp online communicator app. Most such voice communication apps use Opus codec as a supplementary codec. Thanks to high compression ratio offered by Opus it is commonly used for background transmission. Low latency and low computation requirements combined with narrow band make it the code of choice for online game Voice Chats (such as Discord or Teamspeak).
PlayStation 4 implements Opus technology for its hardware in-game chat. Most devices based on RockBox software and select series of iPod devices use this codec for audio playback. Latest audio players based on Android and its derivatives offer support for OPUS files and Opus codec by default.