You can't ping a dial up modem because it is not connected to any network and does not have any way to obtain an IP address. As I mentioned before, cable/DSL modems are a different story since they do have IP addresses which are usually assigned by a DHCP server at your ISP. You might(and it's a big might) be able to assign a private IP to a modem that is connected to a terminal server or RAS but I don't think so. There is such a thing as a LAN modem that is basically a modem with it's own PC/NIC card and acts like a communications server.