gsmsmsrequeue: 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/gsmsmsrequeue - from package: gsm-utils

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

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