freedv: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/freedv - from package: freedv

You may install the required package with command apt-get install {package}

Error in other languages:
freedv: bevel nie gevind nie
freedv: comandă negăsită
freedv: comando não encontrado
freedv: commande introuvable
freedv: command not found
freedv: käsku ei ole
freedv: không tìm thấy lệnh
freedv: komanda nerasta
freedv: Kommando nicht gefunden.
freedv: kommandot finns inte
freedv: komut yok
freedv: nie znaleziono polecenia
freedv: níor aimsíodh an t-ordú
freedv: no se encontró la orden
freedv: no s'ha trobat l'ordre
freedv: opdracht niet gevonden
freedv: parancs nem található
freedv: perintah tidak ditemukan
freedv: príkaz nenájdený
freedv: příkaz nenalezen
freedv: команда не найдена
freedv: командата не е открита
freedv: 命令找不到
freedv: コマンドが見つかりません