caller ID on FXO port

Unanswered Question
Dec 29th, 2007
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Hi all,

I have some trouble with caller id on fxo port

I use cisco router 3800, fxo port

I have 2 phone line from 2 telephone company:

FXO port 1->line 1-> telephone company 1

FXO port 2->line 2-> telephone company 2

2 port are config with "caller-id enable"

When i use debug: Caller ID is show on line 1 (calling number=xxxxxx), on line 2 there is no caller id(calling number= )

When i connect 2 phone line directly to 2 analog phone, 2 phone can show calling number on its lcd screen.

Any one have suggestion ?


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Overall Rating: 3.7 (3 ratings)
paolo bevilacqua Sat, 12/29/2007 - 04:36
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What happens if you connect line 2 to port 1?

Sometime analog lines have different characteristics and need to be tuned on site. Please apply the THL sweep technique to determine optimal impedance:

Hope this helps,please rate post if it does!

conkinkinconkinkin Mon, 12/31/2007 - 01:56
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If i connect line 2 (TelCo 2) to port 1, the caller ID is not show. I tested all 4 port FX0 with line 1, the call ID is show.

I try the THL sweep technique. When have call on port 0/3/2 i try this command:

-test voice port 0/3/2 thl-sweep

-test voice port 0/3/2 thl-sweep verbose

I copy result in attached file, it recommend use complex 1. But after i use complex 1, caller id still not show

When have incoming call, i use debug and see this on line 2:

Calling Number=(TON=Unknown, NPI=Unknown, Screening=Not Screened, Presentation=Allowed),

pemelend Sat, 12/29/2007 - 11:25
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debug vpm signal and vtsp all can help to see what's wrong

try adding the following command under your voice port configuration:

voice-port X/X/X

caller-id alerting dsp-pre-alloc

blackmichael Sat, 12/29/2007 - 20:59
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If you are using call manger and your gateway is running MGCP you will not be able to recive caller id from FXO interfaces. I would sugest chaning your gateway to H.323

conkinkinconkinkin Mon, 12/31/2007 - 02:00
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On my voice gateway i only have command:

(config-voiceport)#caller-id alerting ?

ring during ring


I run H323 and caller id is show on line 1.

Any one have suggestion?

paolo bevilacqua Mon, 12/31/2007 - 02:32
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Seem like there is some subtle difference on the signal for line 2 that prevents the outer from picking up CLID correctly.

I'm afraid your only remedy is to use ISDN BRI where these problems never happens, because it's digital.

fultont Mon, 12/31/2007 - 08:18
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Unfortunately, Caller ID on a FXO port is only supported on a H.323 gateway.


conkinkinconkinkin Wed, 01/02/2008 - 18:47
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I using H323 protocol.

Hi all,

Analog phone support caller id with fsk and dtmf signal.

Maybe cisco FXO card not support one of two signal?

Any one can show me document about caller id signal type support on cisco FXO card?


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