Cisco FXS VIC voltage!!!

[beluja]

I am using cisco 1760 router. I am having problem with the VIC-2FXS lines to PABX. The pabx line voltage measure 24v, but when I connect it to fxs card, the card get damage.

Note, that both pabx and router have grounding.

Now, I do not know what can be the problem. IS THERE ANYONE WHO CAN HELP.

Cisco document says idle voltages for FXS cards are 24 v for low and 48 for high.

 

[burtsbees]

If the pabx measures 24VDC at the end where the card goes into the router, then the voltage is not the problem. First, how does the card get damaged? Second...could it be an incorrect cable?

Burt

 

[kurthansen]

If you are using an FXS card then the Cisco devise should be supplying the voltage not the PBX. You would want to plug into the trunk port of another PBX not the station side of the PBX. FXS to FXO not FXS to FXS. FXS=Station FXO=Trunk

 

[brianinms]

Easy way to remember is FX0 = connect to Office, FXS= connect to Station

 

[beluja]

Thanks, for all inputs.

1. The cause of damage is relacted with electrical discahrge.
2. I want to connect from FXS to FXO (PBX trunk port).

Note that, when I connect a FXS card to a telephone, it works. But, when I try it to PBX an electrical discharge happen.

 

[whykap]

so is the "discharge" coming from the PBX?