Most P25 radios also require a specialized device (keyloader) for loading encryption keys that's separate from the vendor's programming software for channels and other parameters. Used keyloaders that support AES-256 still go for $2,000+ (Motorola KVL3000+/KVL4000).
A couple years ago I developed an open source one:
A couple years ago I developed an open source one:
https://github.com/KFDtool/KFDtool