Multiplexing is the process of sending multiple signals at the same time over the same physical channel. FDM can consist of analogue or digital signals. FDM divides and re-modulates the channel bandwidth into frequency range increments and sends them out. It also re-modulates signals by shifting the signal frequencies into each increment. TDM is only used for digital signals. It breaks information into packets and allocates time slots for users on the channel.

What is statistical multiplexing?
Statistical multiplexing uses more bandwidth for clients who need more, so it allocates according to need and can switch back and forth as needed.

What are the advantages of using a T1 circuit instead of 24 analogue lines?
Total bandwidth of a T1 circuit is 1.544mbs. Advantages include the ability to use two twisted pair wires vs. 24 pairs, 24 connections for the price of 12 and is less subject to interference and static.

What is submultiplexing, and why would we do it?
Allows for more clients to transmit over a single channel by breaking down any or all channels into smaller bandwidth channels. We do this so one circuit can support many users who transmit at slower speeds.

Circuit switching can handle digital or analogue information and uses one dedicated path for the signal from start to end of the transmission. Packet switching routes digital transmissions only and travels the most efficient path over multiple combinations of links.
Which is restricted to same speeds throughout and at each end? Circuit
Which can handle multiple speeds? Packet
Which is better for continuous, uninterrupted signals? Circuit
Which is better for intermittent, bursty traffic? Packet