CSU/DSU and DCE Quesion

[typesh]

Hey everyone,

I am having some problems understanding the CSU/DSU and DCE. I understand that a CSU/DSU is used to connect a DTE (such as a router or computer) to a T1/T3 line. From what I understand, the DTE connects to the CSU/DSU box, and then the CSU/DSU box connects to the circuit. I am a little confused in how that differs from a DCE. I am not really sure on what a DCE is. I understand from Page 30 of Lammle 6th Ed that the DCE is usually located at the service provider. I have researched it online and to me is sounds very similar to a CSU/DSU.

Wikipedia says: A Data circuit-terminating equipment (DCE) is a device that sits between the data terminal equipment (DTE) and a transmission circuit.
It also says that the DCE is a modem.

I though it was the CSU/DSU that sits between the DTE and Transmission Circuit, and I thought the CSU/DSU was the modem.

This has been really confusing...

Any help would be appreciated.

Thank you.