about Call of Duty: Black Ops are answered right here.
Playing online involves having your console or PC send packets of data through multiple servers, hubs and backbones to reach its destination server. Your Internet Service Provider may sometime have equipment fail somewhere, and sections of the network go entirely offline. Other times connections have to be re-routed due to power failures or natural disasters, and as a result your connection time (and game performance) suffers.Why can't I connect to online games?
A common cause of problem with connecting to an online game is a router that needs configuration. While most of the time this isn't necessary, each game is different and it may be required even if you've never done so in the past. The most common type of configuration is port forwarding. Each router has a different menu setup so we can't give you exact instructions on how to do this on this site. You should refer to your router manufacturer or a site like http://portforward.com/ for more assistance.
List of ports to forward:
Nintendo Wii - TCP [443, 3074] UDP [3074, 3075]
PC - TCP  UDP 
PlayStation 3 - TCP [80, 81, 443, 3074, 5223] UDP [3074, 3075, 3478]
Xbox 360 - TCP  UDP [88, 3074]
This may be a problem with the disc, such as scratches or physical damage. If you experience a freeze while playing online, it is also possible that you may be having a network problem.I get a 'DISC READ ERROR' when I try to start the game, why?
Inspect the bottom of your disc for scratches or other damage. If you don't see any try your game on a friend's console, to see if you experience the same problem. If you do experience the same issue contact Activision's Customer Support department for further assistance.My disc is scratched or damaged. Can I get a new one?
The disc is covered by a limited warranty that covers only manufacturing damage. However, you can obtain a new disc as a paid replacement. The fee is usually $20. Please contact Activision's Customer Support department to begin the replacement process.How do I contact customer support for issues or questions not found in this FAQ?
You can visit the Activision Customer Support Website: http://www.activision.com/support Support is also available by phone, call 800-225-6588 between the hours of 7am-7pm PST 7 days a week. Please note that this number is for North American support only.Why have I been banned?
Banning happens as a result of a user not complying with the Call of Duty: Black Ops online security policies. You can read more about the Security & Enforcement Policy by following this link: http://www.callofduty.com/board/viewtopic.php?f=70&t=341470&sid=00tvvrnnn4camd8e5dba32pll4
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