The root cause of the low volume problem is the result of software echo
cancellation software, and its need to insert a noticeable loss. If I
recall correctly, the wctdm.c driver has a statically defined loss value
of something like -6 db that is loaded into the TDM400 chipset at driver
load time.
Ordinarily, that loss is not all that noticeable. But, if your pstn line
is rather lengthy (greater then about 5db worth of loss), the two loss
values become very noticeable and marginal to users. There is no known
fix or workaround.
The low audio becomes even worse when a pstn caller leaves a voicemail
and the user calls in via the pstn to retrieve his voicemail. The
voicemail gain setting was intended to be sort of a workaround, but its
marginal at best.
JD Austin wrote:
I've been fighting with this issue for over a year.
There are several threads here talking about it:
Digium Zaptel volume issues
setting of volume
Low volume/audio problems on TDM400 card
increase the volume ?
There is one thread (Voicemail volume adjustment) that give me hope that
this can be fixed that mentions adding
|usg(10) to the dial command to increase the gain. I'm still a novice at
the inner workings of asterisk so I'm hoping one of the gurus on the
list will figure this out eventually.
JD
Hi all,
we do have the following configuration
(non-Asterisk PBX) - T1 - ZAP (Asterisk PBX) - ZAP - T1 - (GSM
Gateway) -> GSM Enduser
The call is originated on the (non-Asterisk PBX) - gets send over a T1
connection to the asterisk server (which does least cost routing) -
the asterisk server then does send the call over a GSM Gateway into
the world...
The Problem we do have is - that the Users behind the non-Asterisk PBX
are complaining about low volume media if the the calling through the
gateway (if the are calling mobiles...). So i have started to raise
the rxgain value for the connection between the asterisk box and the
GSM Gateway, this does work quite well - but not really perfect. The
ringback (not locally generated - does come from the GSM Provider)
does get terrible loud - as soon as the callee is connected - the
speech is nearly not hearable because it has such a low volume.
The ringback is EARLY MEDIA - if i am right - and the speech is normal
MEDIA. So, is it possible to set different gains for EARLY MEDIA and
normal MEDIA ?
Does anyone else have had this problem ?
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