The Net use command translates to TCP port 139.
While most firewalls will block port 139 at the border, maybe some don’t().
If a firewall is in place, you may need to find a way to own a system inside the border firewalls first….
A primitive way(WinXP/Server 2003,etc ) to see if you can get to a host is run the command
telnet [ip or host name] 139