rmdtovbox: 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 CentOS possible default full paths are:

/usr/bin/rmdtovbox - from package: isdn4k-utils

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/rmdtovbox - from package: isdnvboxclient

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

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