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[jpitlick]

I recently bought an unlocked SPA-3102.  I started setting it up to send calls to an Asterisk PBX.  I am able to receive incoming calls.  I have been unsuccessful in making outbound calls on my PSTN line.  My dial plan on the Line 1 tab is:  (<#,:>xx.<:@gw0>|[2-79]11<:@gw0>|xx.|*xx.|**xx.|<#,:>*xx<:@gw0>)

It may be overkill, but I believe it should work.  When I dial # and then the number I want to call, I hear one ring and then I get a busy signal.  The Last PSTN Disconnect Reason is either CPC Signal or PSTN Disconnect Tone.  What can I check to fix this so that I can make outbound calls?  I am in the US.  Thank you.

[Scorpio-cz]

Hello jpitlick,

this sounds to me like the SPA-3102 does not properly detect/understand the tones your PSTN line generates. So it assumes the line was disconnected (what is CPC signal I have no idea).

[jpitlick]

Great.  Now, how do I fix that?

[hw]

I have seen the problem with my SPA3102. When the SPA3102 takes the FXO port off hook to dial the pstn number it detects a CPC Signal and disconnects the line. The result is as you say.

A CPC signal is a brief interruption of voltage that is used as a signal from a central office that the calling party has hung up. In this case it is a false detection of a CPC signal. You can prove that that is the problem by temporarily disabling detect CPC. I found that I could fix the problem by increasing the Min CPC Duration by 100ms (0.1 sec). I also found that I didn't have the problem if I reversed the two telephone wires so that the voltage was positive instead of negative.

Message Edited by hw on 06-02-2008 08:59 PM

[jpitlick]

Thanks for the info.  I'll try disabling Detect CPC to see if that is the problem.  My Min CPC Duration is set to 0.2 already.  I assume that is 0.2 seconds.  I believe that was the default.  Do you mean that I should increase it to 0.3?  By "the two telephone wires", do you mean switching ring and tip or Line1 and PSTN?  Thanks.

[hw]

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jpitlick wrote:

My Min CPC Duration is set to 0.2 already. I assume that is 0.2 seconds. I believe that was the default. Do you mean that I should increase it to 0.3?

Yes that was the suggestion.

By "the two telephone wires", do you mean switching ring and tip or Line1 and PSTN?

Yes, tip and ring. That reverses the polarity shown on the adapter. I don't know why that makes any difference but it did in my case.

[jpitlick]

Thanks for the help.  I got it working.  It was the Min CPC Duration.  I changed it to 0.6.  I may try to tweak it down to see if it can be lowered.

[hw]

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jpitlick wrote:

Thanks for the help. I got it working. It was the Min CPC Duration. I changed it to 0.6.

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A Google search says that CPC is typically 250ms to 500ms. If you set the minimum duration to 600 ms you may miss a valid disconnect signal.

Thanks for confirming that a false CPC reading was the problem.b

[jpitlick]

I'll try dropping the setting to 0.5.  I tried 0.3 and 0.4 and still had the problem.

[Scorpio-cz]

Hellom possibly you realy have a bad wiring which brings such a dropouts.