Re: [hylafax-users] Failure to receive silence (synchronization failure)

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

Alex R [MaxoTel] wrote:
> The VoIP server that this is on is very close to the terminations, so it
> shouldn't have anything to do with the quality or delay of the VoIP call,
>   

It doesn't have anything to do with the *delay* of the VoIP call.  It 
has everything to do with UDP being a lossy medium.

> plus I can get an identical result every time I do it (unless the VoIP call
> to certain numbers is handled differently at the provider)
>   

I'm not sure that this is relevant.  And it's almost certain that the 
VoIP provider handles calls differently based on destination.

> A friend of mine said he had to adjust the tx/rx volume on his VoIP switch,
> but I'm using Asterisk. Could that be the problem?

Lots of people fax over VoIP.  And lots of people have lots of trouble 
trying to fax over VoIP.  Some of them don't think that they're having 
any trouble.  Some of them just aren't paying close-enough attention to 
realize that they're having trouble faxing over VoIP but that ECM is 
rescuing them.  The end-result of trying to fax over VoIP will be quite 
variable from case to case depending on the circumstances... but unless 
you have some means to significantly mitigate the potential loss on the 
UDP connection, then you can't depend on VoIP to pass data (or fax).

Thanks,

Lee.


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