sipwitch-cgi: 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/sipwitch-cgi - from package: sipwitch-cgi

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

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