[Asterisk-Users] offtopic - channel banks

[James Edwards]

A channel bank allows you to go from DS1 to DS0; i.e. it takes the 24 channels
from a DS1 (T-1) and spins off individual DS0's. 

For instance, you could plug a T-1 PRI (23 channels + 1 channel for signaling)
into a channel bank and get DS0 POTS (plain old telephone service) lines, which 
can drive a standard phone. 

One advantage here is a PRI T-1 is 2 or 4 wires, whereas 24 POTS lines are
48 wires (24 pair), so for a voice provider you can deliver more lines/services 
per pair of wire.

Much the same happens on the T-1 to T-3 side with a wide bank (M13 or EZ T3 mux, ect).
A T3 is 28 T-1's, so a provider can mux up to 28 T-1's from customers into a T-3, meaning fewer
pairs of wire to transport or cross connect. Collocation is priced on U's of rack space
or square footage and is often quite expensive at the LEC's facilities.

T-3 ports are much cheaper (per DS0) than T-1 ports for the provider, who can then use
a relatively cheap wide bank to get T-1's then a channel bank to get DS0's.


-- 
James H. Edwards
Routing and Security Administrator
At the Santa Fe Office: Internet at Cyber Mesa  
jamesh at cybermesa.com
noc at cybermesa.com
(505) 795-7101
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