Why can't ping a wireless broadband modem?

To access a PC behind a router on a normal broadband connection you can use port forwarding (see my post above). That means you set up a rule in the router so that if it sees any traffic on a defined port, e.g. 1234, it will send it to a defined PC, e.g. 10.240.151.128. Then you would add that port number to the public IP so 119.234.1.24:1234. You can use this for remote access, FTP, a webserver, and other services, but ping will not take a port number, so you cannot ping through the router.

2. The other test I did was use two modems and sim cards from the same network provider, hook them up to two PCs. IPCONFIG one modem and get the local IP address in the private network. Then from another PC (with another sim card from same network provider) ping the IP I got from IPCONFIG. No response. So now I am thinking the modems probably is ping blocked, because both of the modem is already connected to their same private network with their local IP and they should be able to easily find each other sitting on the same highway. :oops: So is my concept correct here?

Could be, I have no idea how cell type networks work, but someone else may. Probably would help if you tell us where you are and what network this is.