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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I have had providers install an IAD device where they take the circuit
from the Telco into their IAD. Then they hand of a PRI to my equipment from the
IAD. In this case you need a Crossover T-1 cable.<o:p></o:p></span></p>
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color:#1F497D'><o:p> </o:p></span></p>
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<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
cisco-voip-bounces@puck.nether.net [mailto:cisco-voip-bounces@puck.nether.net] <b>On
Behalf Of </b>Tim Smith<br>
<b>Sent:</b> Wednesday, June 03, 2009 7:37 AM<br>
<b>To:</b> Dane<br>
<b>Cc:</b> cisco-voip@puck.nether.net<br>
<b>Subject:</b> Re: [cisco-voip] T1 xover or straight through?<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'>Hi Dane..<br>
<br>
Simple rule for this.<br>
<br>
1. Customer Equipment to Customer Equipment = T1/E1 cross over cable<br>
2. Customer Equipment to Network = Straight through cable<br>
<br>
Customer Equipment = PBX, Voice cards on routers, key systems <br>
Network = the PSTN, your carrier, etc<br>
<br>
Bit more info to help explain hopefully :)<br>
<br>
Your 3845 T1 voice interface has pin outs as follows<br>
<br>
Pin<br>
1 - Receive (RX) Ring<br>
2 - RX Tip<br>
4 - Transmit (TX) Ring<br>
5 - TX Tip<br>
<br>
Think of receive as your ear and transmit as your mouth<br>
Straight through cables connect pin 1 to 1, 2 to 2, 4 to 4, 5 to 5.<br>
<br>
So when connecting customer to customer equipment with a straight through cable<br>
You are essentially connecting ear to ear and mouth to mouth.<br>
To get complete circuits you need ear to mouth and mouth to ear<br>
<br>
An E1/T1 cross over cable "crosses" the RX and TX connections as
follows:<br>
Pin 1 to Pin 4<br>
Pin 2 to Pin 5<br>
Pin 4 to Pin 1<br>
Pin 5 to Pin 2<br>
<br>
Network / PSTN equipment has different pinouts.. i.e. it expects RX on pin's 1
and 2, and expects TX on Pins 4 and 5 from your equipment. Hence straight
through cable required.<br>
<br>
Also dont forget if this is ISDN you also have a layer 2 network / user element
to consider. i.e. if you connect 2 x customer equipment together - one side
needs to be configured as Network side, and the other as user.<br>
<br>
Hope this helps a bit..<br>
<br>
Cheers,<br>
<br>
Tim<o:p></o:p></p>
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<p class=MsoNormal>On Wed, Jun 3, 2009 at 7:04 PM, Dane <<a
href="mailto:dane@pktloss.net">dane@pktloss.net</a>> wrote:<o:p></o:p></p>
<p class=MsoNormal>First I wanted to say thanks for the replies and
information.<br>
<br>
Second, well I got it sorted out finally. I took down one of the<br>
PRI's after hours from the IAD and connected it to the 3845 with a<br>
straight through cable just to test. It did not come up which is what<br>
I think I and everyone who responded on this list would have expected.<br>
I connected the IAD to the 3845 with a T1 crossover just as I have<br>
the IAD connected to my CMM-6T1s and it came up.<br>
<br>
Now the kicker is that this same 3845 T1/PRI port connected to the<br>
AT&T demarc requires a straight through cable.<br>
<br>
I have to be honest and admit that this confuses me. Of course its<br>
4am and I have been busting my ass since 6am so I am not able to<br>
mentally sort this out. Have to give it some thought when I have my<br>
wits how the 3845 port takes either a T1 crossover or a straight<br>
through depending on the other side apparently.<br>
<br>
Anyway, I thought it was interesting to note and share.<br>
<br>
Thanks again for the help.<br>
<br>
<br>
<br>
<br>
<br>
On Mon, Jun 1, 2009 at 12:31 PM, Go0se<<a href="mailto:me@go0se.com">me@go0se.com</a>>
wrote:<br>
> As a general rule a T1 crossover cable is always required between PBXs no<br>
> matter how you interconnect them. I'm not aware of a T1 controller that
will<br>
> auto-mdix. You can build your own T1 crossover - cross pins 1&2 to
pins 4&5.<br>
> (1 to 4 and 2 to 5)<br>
><br>
> -Go0se<br>
> <a href="http://atc.go0se.com" target="_blank">http://atc.go0se.com</a><br>
><br>
> -----Original Message-----<br>
> From: <a href="mailto:cisco-voip-bounces@puck.nether.net">cisco-voip-bounces@puck.nether.net</a><br>
> [mailto:<a href="mailto:cisco-voip-bounces@puck.nether.net">cisco-voip-bounces@puck.nether.net</a>]
On Behalf Of Dane<br>
> Sent: Monday, June 01, 2009 11:28 AM<br>
> To: <a href="mailto:cisco-voip@puck.nether.net">cisco-voip@puck.nether.net</a><br>
> Subject: [cisco-voip] T1 xover or straight through?<br>
><br>
> Anyone know if you need a straight through or t1 crossover to go from<br>
> an IAD to a 3845 with a PRI port? We have some IAD's that terminate<br>
> with CMM's and those use t1 crossovers. Not sure about the 3845<br>
> ports.<br>
><br>
> Connecting to AT&T circuits to the 3845's required straight through.<br>
> Wish I had one to test.<br>
><br>
> Just wondering if anyone might know, wondering if the 3845s can handle<br>
> either / or, and if the requirement comes from the demarc side (either<br>
> AT&T or IAD's).<br>
> _______________________________________________<br>
> cisco-voip mailing list<br>
> <a href="mailto:cisco-voip@puck.nether.net">cisco-voip@puck.nether.net</a><br>
> <a href="https://puck.nether.net/mailman/listinfo/cisco-voip"
target="_blank">https://puck.nether.net/mailman/listinfo/cisco-voip</a><br>
><br>
><br>
><br>
><br>
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