utalk: 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/utalk - from package: utalk

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

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