SNR Transfers - Low Volume

[Tim-Saunders]

About 15% of the calls that my UC540 transfers to my cell phone via SNR have little to no volume.  Has anyone else experienced this?  What can I do about this?  It is really annoying and isn't good for business.

[David Harper]

What sort of trunks are you using to connect to the PSTN?  Analog, ISDN or SIP?  I'll take a stab and guess that you are using analog, in which case one reason a proportion of calls is having problems might be because there is a single trunk with excessive attenuation applied - either at the UC500 end or the telephone exchange.

In any case, the symptoms do sound like a line levels problem, and so I'd suggest you give the support centre a call and have an engineer work through the box with you to adjust the levels to give you a more consistent behaviour.

Cheers,

Dave.

[Tim-Saunders]

You are correct.  I am using PSTN trunks.

I will give the suport center a call.

[David Harper]

Just be aware that this might be a somewhat fiddly and timeconsuming process.  If I am right, then you have one or two trunks with significantly different loss levels to the others and tracking them down might take a little while.  If you have the phone numbers for the individual trunks, you could place test calls to each trunk in turn from the same phone and answering with the same extension on the system and note the levels you receive.  With luck you will be able to hear the difference on one or two of the trunks.  If you can identify the problem trunks that way, then fixing the problem should be a lot simpler.  If you can't - either because you can't dial the trunks directly or because you can't hear any difference, then it may take quite a bit longer to resolve.

In any case, the support engineer should work through all this with you.

Cheers,

Dave.

[Arthur Kant]

Hello there, I wanted to jump in here and say that I am having the same problems with FXO trunks (non SNR scenario just simple call-forward-all to PSTN phone) .  In regard to your comments on the attenuation and troubleshooting these issues with TAC or the support center: I would assume that an attenuation problem on FXO port / analog line would be consistent for types of calls coming into the system not just a forwarded call?  All of our calls sound great in and out of the system until we go through this process then it sounds horribly low to both parties in the call.

[David Trad]

Hi There Arthur,

I would assume that an attenuation problem on FXO port / analog line 
would be consistent for types of calls coming into the system not just a
 forwarded call?  All of our calls sound great in and out of the system 
until we go through this process then it sounds horribly low to both 
parties in the call. 

Line volume, or attenuation as it is being referred to here is a hard one to work on, purely for the following reasons:

• Every single trunk line has its own chararistics, no two are the same
• Each trunk line has its own attenuation levels as well, they might sound fine and dandy, the problem however surfaces when you bridge two trunk lines together, and what makes it worse is that the one that is the noisiest, it becomes the dominant one (I think I explained that right).
• FXO/PSTN (Or as I call it analogue) lines were not really designed for call bridging, not like ISDN which is digital and the signaling frequencies are much more cleaner and with far less interferences

I guess what I am saying is that this problem has been long in existance, it has always been a hit and miss thing, and the more people begin to understand the physical limitation of analogue lines, the better, that way people will move either to a digital trunk line service or a VoIP trunk line service, both of them do not suffer from this problem (SIP/H.323 may at times if it resides on a poorly configured network).

There is no definitive way to resolve this problem and the success rate on resolving it is less then 30%.

Cheers,

David.