[VoiceOps] T1 Crossover Cable

Jay Hennigan jay at west.net
Fri Oct 31 14:18:51 EDT 2014

On 10/31/14, 6:17 AM, David Wessell wrote:
> So two different answers :)
> It's a 904 connecting on the t1 0/2 DSX interface.
> The main issue is that we keep getting D channel is DOWN.

If the T1 interface itself is up, the cable is correct.

The 904 has two T1 interfaces and only T1 0/2 can be used for PRI. When
connecting this to a PBX, a straight-through cable is most common.

Any of the "e" series TA900 flavors have four T1 interfaces. T1 0/3
and/or T1 0/4 can be used for PRI, and these will generally need a T1
crossover (1,2 swapped with 5,4) to go to a PBX.

If the T1 is up but the D-channel is down, it isn't the cable. Check
timing source, switch type, that the PBX uses channel 24 for D-channel,
user vs. network role configuration, etc.

Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net
Impulse Internet Service  -  http://www.impulse.net/
Your local telephone and internet company - 805 884-6323 - WB6RDV

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