connection between isp and my exchange

[mr.bond]

from my exchange i can telnet to isp server on port 25 bt not from ISP.i have firewall in between when i am pinging my public ip it is showing the following on my router which is on outside world on public IP's.other exchange servers are running fine

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 212.116.203.5, timeout is 2 seconds:

UUUUU

Success rate is 0 percent (0/5)

[rais]

To enable access to your Exchange/SMTP gateway, just open up port 25 on your firewall. In Cisco's PIX, this is done using 'static' command.

Looks like your ICMPs are disabled as well, which I dont think is a default feature of PIX.

Thanks.