9 Mar
2004
9 Mar
'04
12:21 p.m.
R. D. Davis <rdd(a)rddavis.org> wrote:
This is interesting. Why then do DECvoice and Fallon
FAX cards, for a
Qbus VAX, have connectors for a T1 line on them? Not being very
familiar with telephone equipment with T1 lines, perhaps I'm
overlooking something. Any thoughts on this?
In telephony applications a T1 is split into 24 channels each carrying a phone
call. When, however, someone speaks about T1 as a dedicated line for Inet, a
device called a CSU/DSU takes the entire T1 payload (all 24 channels together)
and turns it into an EIA-422 or V.35 synchronous serial stream that a router
then has to deal with. In fractional T1 applications the CSU/DSU is
reconfigured to take fewer than all 24 channels, reducing the bit rate on the
EIA-422 or V.35 line.
MS