The Codec2 project has developed FreeDV, a program to encode digital voice on two-way radio in only 1.125 KHz of bandwidth.
But FCC regulations aren't up-to-speed with the challenges of software-defined radio and Open Source.
24 page FCC filing proposes that FCC allow all digital modulations and
published digital codes on ham radio and switch to bandwidth-based
You can read more on Bruce Perens K6BP blog - http://perens.com/blog/2013/01/17/1/