faxmodem: 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 CentOS possible default full paths are:

/usr/sbin/faxmodem - from package: hylafax+

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/sbin/faxmodem - from package: hylafax-server

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

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