sipdump: 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/sipdump - from package: sipcrack

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

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