A Network Operations Center (NOC) and it's uses varies from provider to provider, but most provide a number of services to both customers and non-customers alike.
Most NOCs are the front line for customer support, for a wide range of issues, including emergency support for folks encountering Denial of Service attacks, loss of connectivity, and security issues.
Some companies have Customer Service centers that escalate internally to their NOC for outages that affect more than one customer. An example may be if your T1 is down and it is delivered to your provider via a CT3 and the entire CT3 is down the NOC would work on the single DS3/CT3 outage instead of the 28 individual customer outages.
Some companies reserve their NOC for inter-company and intra-company communications and do not speak directly to customers except in the rare case that they require additional information and their Customer Service Center fails to collect the information or lacks the technical skills to properly collect the information.
When contacting another NOC, Identify yourself, the company you represent and clearly describe the problem you are having. Do not contact a NOC if you are a customer of the company unless that is your direct support mechanisim. This can lead to the lack of tracking of your problem and inability to obtain credits under your SLA or other support problems.
One should also not become abusive when talking to NOC staff. Their jobs can be extremely stressful especially during late-night shifts where staffing tends to be minimal. (00:00-8:30 local time to your NOC)
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