Backup solution for remote site which ioslated from domain?

We are currently using Symantec Netbackup for our enterprise backup solution. Our current challenge is to find a backup solution for bunch of remote offices which not in our network. Each site has around 5 to 20 server/desktop need to be backed up (<500GB). We think iCloud may be the solution. Does anyone know if Symantec netbackup already started iCloud support? And what kind of backup solution you are using if you have same backup request?