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New Member

ATA186, 827-4v, 5850 - fax, modem passthrough

there are problems. :-)

We have following devices: ata186 (2.15), 827-4v (12.2-4.YA3), 5850 (12.2(2)XB7).

Ata, 827 are used as end-points and 5850 - core logical function. There is task: adjust ATA, 827 to solve voice,(analog) modem, fax calls to outside (send) and back (receive mode). I.e. these devices have to pass voice, modem and fax signals in both directions via 5850 as central point.

We came to the following decision:


dial-peer voice 100 voip

incoming called-number .T

voice-class codec 1

fax rate disable

fax protocol none

no vad


dial-peer voice 300 voip

codec g711ulaw

fax rate disable

fax protocol none

no vad


AudioMode:0x00120012 (disable fax detection)

I.e. voice pass OK in both directions, fax pass -OK (but only a deceit - 'fax rate disable') in both directions, modem pass at 9600 only from 827-4v to ouside ( dont back).....

It is known, that ata 186-support fax Pass-through; Cisco 827 - Pass-through, Relay; 5850 - Relay (dont support modem pass-through). ONLY!

When all these devices will support T.38 and modem pass-through?

Maybe another decisions? (based on another IOS or Hardware versions?

So, how to make our dreams come TRUE?

New Member

Re: ATA186, 827-4v, 5850 - fax, modem passthrough

I found lot of tips and Q&A on ATA and other VoIP stuff on this page. Maybe you can take a quick look at it