Unable to fax between two ATA 187 attached fax machines

[junior.beatty]

I have two fax machines attached to the VOIP network using ATA 187's using the T38 fax relay.  I am unable to send faxes between the two devices.  Has anybody experienced this issue and if so what did you do to resolve the issue.  Tried fax passthrough with no luck.  Also set the dial peer on the voice gateway to use the T38 fax protocol.  Thanks for any info.

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[junior.beatty]

Looks like I just answered my own question.  Since both of these devices are on the internal VOIP network, 4 digit dialing between devices worked.  I am able to send between the two ATA attached fax machines.  Originally I was trying to go outside, using 9xxxxxxx, which did not work.