sflphone-client-gnome: 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/sflphone-client-gnome - from package: sflphone-gnome

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

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