It actually looks like the master servers are having some problems at the moment, and that's why you're unable to connect.
This is being looked into, and we're hoping to have an update for all our classic CoD players soon.
Is there any progress with the Master Servers?
The server is down for around 1 week.
A few information about the progress would be helpfull.
a) What triggered the server crash?
b) How long it will be needed to fix it?
c) Why it takes already 1 week?
d) Where can we find informationen related to that issue?
e) Is there any "News" Page to find out these issues in the future on a central information basis?
It would be very nice to get some feedback!