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Home > Archive > Voice Over IP in UK > September 2007 > SPA3102 PSTN Audio quality
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SPA3102 PSTN Audio quality
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| I'm using an SPA3102 in conjunction with a GSM premicell. When dialling
out over the mobile network, although I can hear the caller perfectly
well, they experience clipping of the audio at their end.
If a POTS phone is plugged into the premicell, no clipping occurs. If
the SPA is powered off, no clipping occurs.
I have tweaked & tweaked.
Has anyone got any specific "must have" settings for this device to
improve the PSTN audio quality?
If the device wasn't remote, I'd try it in a BT line. Alas, I cannot at
the moment.
Cheers.
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| Christian 2007-09-07, 7:11 pm |
| Hi Jono,
> I'm using an SPA3102 in conjunction with a GSM premicell. When dialling
> out over the mobile network, although I can hear the caller perfectly
> well, they experience clipping of the audio at their end.
In the webinterface of the SPA, under the tab "regional", you can find a
setting "FXS port input gain". If you set this at a lower level, this should
decrease the audio level towards your premicell. Try it with steps of 3 (dB)
at a time. A good start value is -3 (that is what I believe is the default).
Negative values mean a reduction, positive values mean amplification of the
audio signal.
Oh... if you don't hear any difference at all, then this is my fault: I
always seem to confuse FXO/FXS input and output signals. If I screwed up:
you need to do the described procedure with the "FXS port output gain" :-)
Hope this helps...
Christian
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| Christian 2007-09-07, 7:11 pm |
| > I'm using an SPA3102 in conjunction with a GSM premicell. When
> dialling out over the mobile network, although I can hear the caller
> perfectly well, they experience clipping of the audio at their end.
You know what: I screwed up already :-) Never mind my earlier post, you
need to adapt the audio level from the SPA towards your PSTN line (the
premicell). The recommendation I made in the previous post would work but
would also affect the audio-levels on your VOIP-calls.
So... second attempt: in the webinterface of the SPA, under the tab "PSTN
line", you can find a setting "SPA To PSTN Gain" (at the bottom of the
page). If you set this at a lower level, this should decrease the audio
level towards your premicell. Try it with steps of 3 (dB) at a time. A good
start value is 0 (that is what I believe is the default). Negative values
mean a reduction, positive values mean amplification of the audio signal
towards the PSTN-line.
Hope I really helped you this time :-)
Christian
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| Christian submitted this idea :
>
> You know what: I screwed up already :-) Never mind my earlier post, you need
> to adapt the audio level from the SPA towards your PSTN line (the premicell).
> The recommendation I made in the previous post would work but would also
> affect the audio-levels on your VOIP-calls.
>
> So... second attempt: in the webinterface of the SPA, under the tab "PSTN
> line", you can find a setting "SPA To PSTN Gain" (at the bottom of the page).
> If you set this at a lower level, this should decrease the audio level
> towards your premicell. Try it with steps of 3 (dB) at a time. A good start
> value is 0 (that is what I believe is the default). Negative values mean a
> reduction, positive values mean amplification of the audio signal towards the
> PSTN-line.
>
> Hope I really helped you this time :-)
> Christian
Cheers
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