the default FTP port is 21, not 23 (telnet), and the FTP data port is 20.
The data transfer itself will be accomplished through an high tcp port of the range 1024-65535.
Current routers do allow any traffic from inside the local network to the internet and uses stateful package inspection firewalls, so that even FTP, that negotiates high tcp ports for data transmission, will automatically get opened by the router, if it relates to the current ftp connection.
So FTP should generally work.
Best is, to first ask the IT guys of the company, which restrictions might block the connection from the home network.