In the two-way radio world, most protocols are open (P25, DMR, LMR, etc.) but almost every digital protocol uses the AMBE[1] voice codec, which is not.
AMBE in most equipment was provided in a physical chip for protection however some firmware implementations existed in hardware from big players and they were reverse-engineered.
Most of the Chinese B-brand (AliExpress stuff) radios use this reverse-engineered software implementation. They're not licensed but a Chinese company pretends to license this on behalf of DVSI though it's totally illegal. The A-brands like hytera use the official one of course.
See the popup warning on this page: https://www.dvsinc.com/soft_products/software.shtml
Since the closed nature of this codec goes counter to ham radio principles some open source codecs were also developed. The best example is codec2.