dtmfcheck: 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/dtmfcheck - from package: vpb-utils

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

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