[Freeswitch-users] Which ATAs to chose for modem connections?

Steve Underwood steveu at coppice.org
Mon Dec 14 04:29:02 PST 2009

On 12/14/2009 08:05 PM, Peter P GMX wrote:
> We currently use Patton gateways SN4116 for attaching fax and modem
> equipment to our Freeswitch system. Freeswitch is in bypass-media-mode,
> so media flow goes the following way:
> Modem/Fax =>  Patton_SN4116 =>  Patton_SN46XX =>PSTN/ISDN
> However modem connections are not very reliable. We exchanged the SN4118
> against a "Fritzbox" ATA and the situation improves. However Fritzboxes
> do not deliver the number of ports we need.
> What is your experience? Which ATA is the best choice for modem connections?
> Best regards
> Peter
Your improvement is probably more due to luck than engineering.

Turning off any dynamic jitter buffering, and making sure you use only 
A-law or u-law, will reduce the failures. the only thing that will give 
reliable results for modems is a managed, absolutely lossless, packet 
path, and terminal equipment which does doesn't slip data samples to 
allow for mismatched sampling clocks. Good luck finding those.


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