Updated 2009 May 21

CSUS Communications Jack - Frequently Asked Questions

What is a jack?
What services are available on jacks?
What kinds of cables connect the jacks to the equipment?
How are the jacks labeled?

Q: What is a jack?

A: A "jack" is a connector mounted on the wall or floor, intended to carry low-voltage electrical signals. The jacks in the CSUS buildings are RJ-45 8-conductor connectors wired per TIA-568B to 4-pair unshielded twisted-pair cables which run to central telecommunications closets in each building, where they can be connected to equipment which provides a variety of communications services.

Click on the image below for more detail on the different types of jacks:

Jack Types

Q: What services are available on jacks?

A: A jack could have any of the following connections:

Telephone services are almost always on the Voice jack, or the lower-numbered jacks in blue-jack clusters.
Data services are almost always on the Data or Network jacks, or the higher-numbered jacks in blue-jack clusters.
There are rare exceptions.

Warning! Since a jack could have any of a number of services connected to it, and since connecting equipment to an incompatible service can damage the equipment or the service, we strongly recommend not plugging equipment into a jack unless you know them to match.

Q: What kinds of cables connect the jacks to the equipment?

A: There are even more types of cables than of jacks. Some of them will cause connections to fail or perform poorly even if their plugs fit into the jacks. Some of them will appear to work, but will cause subtle problems, such as using non-twisted-pair cables for LAN connections.

Q: How are the jacks labeled?

A: That depends on the age of the jacks.

Many buildings on campus were rewired by the ITRP project in 2005. In these buildings, and in buildings built subsequently, there are blue jacks in clusters labeled according to the telco room they are served from rather than by the room the jack is in. The plate label is the telco room number, and the jack label is the patch point within the telco room.

For these, we need:

Older jacks use a different system. The number is in 4 parts:

The later numbers, and the pre-ITRP standard for labeling, has 4-digit building and room numbers and 3-digit jack numbers.

The first example jack cluster has "36 319x02" written on the plate; this means building 36 (Science), room 319, second jack cluster.
The upper jack, labeled "Voice", would be referred to as 0036 0319X002V.
The lower jack, labeled "Data", would be referred to as 0036 0319X002D.

It also has 360322A02 written on a small label; this decodes to building 36 (Science), room 322A, second jack cluster, etc. It is not uncommon for remodeling to cause room numbers to change; afterwards, the jacks may or may not be relabeled to match... and in this case, the jacks were relabeled, but the old labels were not removed. It gets worse: the other end of the cable leading from each jack, in the wiring closet where hundreds of cables come together, may or may not have been relabeled.