[click]

I have recently bought Sipura's SPA 3000 and I have a problem with accessing PSTN line from FXS port. Audio signal is not stable (constantly fading and amplifying) from FXS side only (FXS to PSTN). Other direction is correct. The best way to hear that something is wrong is when I dial #9 (<#9:@gw0>) dial tone supplied by BT is a bit distorted and constantly floating - fading and returning back. It can be explained by the effect as someone is taking off hook another telephone parallely connected to that line and returning it on hook after a second or so.

There aren't any problems calling numbers on the Line 1 (over SIP).

Since I am using SPA in UK, following what is said here on forums I have set following parameters:

FXO Port Impedance: 370+620||310nF
SPA To PSTN Gain: 8
PSTN To SPA Gain: 8

FXS Port Impedance: 370+620||310nF
FXS Port Input Gain: -1
FXS Port Output Gain: -1

while other parameters are, I believe, set as by default.

Version of software is 2.0.11(GWg) and hardware 2.0.1(818a).

Am I missing something? Is there anything I can do?

[PhoneBoy]

If you unplug the SPA3000, which should just be passthrough to the PSTN at that point, do you hear the same thing?

[click]

No. It's only when SPA3000 is working. If I pick up the phone and dial to PSTN (in my case #9), listen to a bit distorted dial tone, and then unplug power from SPA - tone will become slightly louder and not distorted at all.

[o_olivier]

I have the same problem on a PSTN->FXO->Asterisk->FXS->Phone set-up. Try to lower the SPA To PSTN Gain & PSTN To SPA Gain in 1 notch increment starting from 8. I find that everything above 6 gives me too much boost and creates background noise for both parties. I have yet to find the optimal set-up. Any happy UK users outthere ready to share their set-up?
Also, I have lost my voice-mail notification, since I have used the (excellent) wizards to mimic UK dialtones and Asterisk set-up.