FXS Port Crossover

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Mar 11th, 2009
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I am just setting up a new SPA9000 to replace my PAP2.

I have 2 analog phones plugged in to the FXS ports. When I pick up one phone the ringing light comes on on the other. Similarly if I pick up both phones I get 2 dialling tones but both phones are connected. What am I doing wrong?

If I only have one phone plugged in there is no problem. The unit is registering to my voip providers and calls are going in and out OK.


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bgrunewald Wed, 03/11/2009 - 20:36
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Check the RJ-11 cables. Try using 2 wire cables instead of 4 wire.

Don't know the Linksys products, but have seen other Cisco gear that has problems when the pair wrapped around tip and ring (old yellow/black) are connected.

Alberto Montilla Thu, 03/12/2009 - 04:38
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  • Cisco Employee,

I suggest you try connecting the phones with two wires cable only instead of using the 4 wires cable.

There is a feature on the ports which allows you to carry both lines over one 4 wires cable. Unfortunately this feature causes an issue with some phone models when you use 4 wires on each port. This is solved by using two wires cable (the basic telephone cables).



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