From: Dave Gingrich (Dave@xxxxxxx)
Date: Mon Apr 24 2000 - 08:46:04 GMT-3
At 02:01 PM 4/24/00 +0800, zheng jiang gu wrote:
>
>SO WHICH ONE IS RIGHT:
>PBX------------------CISCO PBX---------------CISCO
>1 T1----------------5 T1 1 T1----------------6 T
>2 R1----------------4 R1 2 R1----------------3 R
>9 T-----------------6 T 9 T-----------------5 T1
>10 R----------------3 R 10 R----------------4 R1
>17 E----------------7 E 17 E----------------2 M
>18 M----------------2 M 18 M----------------7 E
>
>PLS HELP ME
If the Cisco and PBX are connected back to back (no telco circuit
involved), then the diagram on the right is correct. If you are connecting
to a telco circuit, the telco will generally (at least in North America)
make all the lead swaps, therefore the drawing on the left would apply.
Think of the E lead as "receive signaling" (ear) and the M lead as
"transmit signaling" (mouth). Sort of like transmit data and receive data
in an RS-232 connection (or more accurately like DSR/DTR). Then of course,
the transmit and receive audio pairs must be swapped as you have indicated
on the right.
Once it is wired correctly, then the signaling (supervision) method
configured on the PBX and the router must be compatible, i.e. wink start,
immediate start, delay dial, etc. On the PBX, the signaling method chosen
may affect whether or not dial tone is delivered. Also the signaling method
can be different for outgoing calls and incoming calls.
If that isn't enough, you must also be aware of what the transmit and
receive transmission levels are. Most of the time today, it is 0db in and
out, but it hasn't always been that way.
-dg
=====================
Dave Gingrich, K9DC
Indianapolis, Indiana
Dave@dcg.org
=====================
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