gvi: command not found

Have You tried accessing the binary with the full path?

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/bin/gvi - from package: python-googlevoice

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