From Agree Software:
Agree Free MP3 to AMR Converter is powerful AMR converter which can help you convert your MP3 files to AMR format used by your cell phone. Agree Free MP3 to AMR Converter can convert MP3 to AMR with ease. The conversion is performed in batch mode, which means that you can easily convert an entire list of audio files to and from AMR with very little effort. All the conversion process is fast and simple, and the output quality is also adjustable. Version 5 may include unspecified updates, enhancements, or bug fixes.
What's new in this version:
Version 5 may include unspecified updates, enhancements, or bug fixes.
It wants you to delete all other codec packages, which I need for all my video editing software. It wouldn't read an mp3 file that works in all other programs.
Although it says it's freeware, you get nag screens to purchase pro version right away, and some features don't work in "free" version. It's not freeware. Don't bother trying it, you'll be disappointed.