[Asterisk-Users] SPA-3000 and quiet voicemail

[Shadow Roldan]

I've experienced the exact same issue with SPA3k's as well as with zap
channels. I do believe it's all related to bug 2023 (db loss in
voicemail) and have yet to find a proper solution. I've tried a variety
of options from writing out to gsm to raw format all to no avail.

If you read through the comments on that bug you will see that there are
others having the same issue with the sipura's as fxo adapters.

I'm looking into the sox gain adjustment thing but haven't had time to
address it, if I do find a solution I'll post back.

Shadow



-----Original Message-----
From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Rich
Adamson
Sent: Thursday, April 14, 2005 6:24 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [Asterisk-Users] SPA-3000 and quiet voicemail


> I have a Sipura SPA-3000 for access to my standard analog PSTN line.  
> I have the SPA-3000 answering and then directing all calls into
Asterisk.
> 
> This setup is working fine for everything except voicemail.  Most, 
> about
> 2/3 or so, of messages left come across very quiet when the voicemail 
> is played back.  A regular conversation with these people, regardless 
> of the phone used on my end, works just fine.
> 
> I did some googling and came up with two links of similar problems, 
> but only for people that are using Zaptel cards:
> 
> http://lists.digium.com/pipermail/asterisk-users/2005-March/096485.htm
> l
> http://bugs.digium.com/bug_view_page.php?bug_id=0002023
> 
> I can't figure out what is going on with the SPA-3000 setup I've got, 
> and it's really odd that everything except voicemail works perfectly.
> 
> Suggestions would be most welcome.

Best guess is that your issue is unrelated to bug 2023. But, the only
way to prove that is to use a transmission test set to send a tone of a
known level through the spa3k to voicemail and then use the test set to
measure the playback. Take a look at bug 2022 on how that was done
(2022 and 2023 are directly related).

You might find http://www.routers.com/asteriskprob/asterisk-config.htm
to be usefull as well.

The audio level to/from your spa is highly dependent on how far away
from the telco's central office you are located. For example, if you're
15,000 feet away (length of the telco's cables, not the point- to-point
distance), the cable loss will be about 6db. The further away you are,
the larger the loss.

It would be very interesting to know exactly what that cable loss
happens to be in your case. It also can be measured by accessing your
telco's milliwatt generator from your location (see the url noted
above).

If you can determine that loss, then point your browser to the spa's
"pstn line" page, and near the bottom change the "spa to pstn gain"
and "pstn to spa gain" to higher values. You might try increasing those
values by +3db at a time, save and reboot the spa, and test the result
using an ordinary analog phone. Changing the values to high will likely
result in some amount of echo, and possibly enough distortion to dtmf
tones to make the spa unusable, callerid to fail, etc.

There seems to be at least some opinion the voicemail audio level
problem might be related to exactly which codecs and voicemail recording
format is being used. In very general terms, the g711
(phone/spa) to gsm (vm format) has a greater audio level loss then does
g711 to wav format (as one example only).

If you have configured your spa pstn -> asterisk to use g729, then try
changing it back to g711 to see what impact that might have.

Saying the above in a reverse sense, leaving a voicemail via a sip phone
verses an spa3k (w/g711) is exactly the same audio levels.
The only variable left is the spa3k -> telco loss (and spa3k level
settings).


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