Cisco ATA 190 settings for a fax machine - having frequent problems with fax machines not negotiating

I have a Cisco UCM voip system that I am admittedly a rookie at.  We recently went through a reorganization of equipment and six of our fax machines were moved to different locations within the building.  We were trying to get off POTS lines anyway so we decided to purchase Cisco ATA 190 devices so that our Ricoh MFP devices could participate on the digital phone system.  These installed just fine and have worked fine, or so we thought.  After being on them for a month or two I am getting a lot more help desk calls stating that incoming faxes are taking forever or failing altogether.  For example, I have a site that faxes here quite often.  When they fax it will often times take 20 minutes to receive a fax from them successfully when the fax machine here isn't busy doing anything else and the other side is not busy either.  In another instance, I had a different facility report that they could not fax to us.  I happened to have the speaker turned on in that Ricoh MFP and I could hear it pick up and try to negotiate and then it would drop the call.  The process would repeat dozens of times and then a fax would finally come through.

I am curious if there are any settings in the ATA 190 that I need to tweak or if there is something that needs to be tweaked in Cisco UCM for the device?  Nothing in the interface on the ATA 190 sticks out at me and I don't even see a setting to lower the baud rate.  I did set up the ATA to send debug messages to a syslog server so maybe that will yield something.  Just looking for people who have implemented these with success that may have some tips.  Thanks.
Steve BantzIT ManagerAsked:
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Steve BantzIT ManagerAuthor Commented:
I have been capturing debug information on my syslog server for a single ATA 190.  I had a test fax sent at 11:30am and I have attached the resulting log.  I have no idea what any of this means but it sure seems like something is failing forcing the remote fax machine to retry.
What is the call path (PSTN connectivity, Type of Voice Gateway, etc) See example below

PSTN -- PRI/POTS/SIP -- Voice Gateway -- MGCP/H323/SIP -- CUCM -- ATA 190 -- Fax Machine

Also, I do not see an attachment in the previous post.
Steve BantzIT ManagerAuthor Commented:
I think I may have figured it out.   Our path goes PRI->Voice Gateway->h323->CUCM->ATA->Fax

With the help of the former IT guy, I was looking in the configuration of the switch port that the ATA is connected to and I noticed that the port was not on our voice VLAN (it was on our regular data VLAN) and did not have the auto qos settings we normally apply to ports that are home to our Cisco phones.  I put the port on our voice VLAN, applied qos for voip and rebooted the ATA.  I made sure the ATA had registered in CUCM and it did have a correct ip issued to our voice vlan.  I tested a fax from a problematic party and it came through on the first try.  I don't want to claim victory just yet.  I am just wondering why it worked at all when the ATA didn't have qos settings applied?  I would have thought it wouldn't have worked at all.
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Steve BantzIT ManagerAuthor Commented:
Well scratch that.  I ran another test and observed the fax machine picking up a call, communicating for a brief moment and then the transmission stops.  I wait a minute or so and the sending fax makes another attempt.  I can't make heads or tails of the attached debug log but what I am showing here is the repeated attempts.
You have to make sure that the phone number assigned to the incoming/outgoing fax is handled on the provider's side so they configure it accordingly as a fax line. In short, a voice call that gets a slight interruption in the data stream, the two parties can resume a conversation when missed, misinterpreted. A fax following a negotiation, an interruption delay will break the connection.

Often, the provider service should provide a list of your dids so that you can designate fax, or other data type of lines....

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Steve BantzIT ManagerAuthor Commented:
I MIGHT be onto something but I am still testing.  I logged into our Cisco voice gateway and saw that voip was configured for:
fax protocol pass-through g711ulaw
modem passthrough nse codec g711ulaw

When I logged into CUCM I saw that the default setting for fax mode for an ATA 190 was T.38 Fax Relay.  I changed that to NSE Fax pass-through—g711ulaw.  All test faxes from the outside to us made it through.  I am still waiting for a bigger sample size before declaring victory.

What I don't get is, if there was a misconfiguration I would think it wouldn't work at all?
Misconfiguration is not the term

VoIP service provider <=> cucm pbx <=> ata190
The connection from at a to cucm is negotiated, the VoIP provider to pbx is negotiated, if there are difference the process includes transition/translation, potentially  interruption, delay cause a drop.

Besides fax machine you could have fax to email, .....ifax.

Check the cucm manual which fax is preferred, the one on the ATA might be .....
Steve BantzIT ManagerAuthor Commented:
All faxes have been successful so far, fingers crossed.

The below was how the voice gateway was set up:
This is how the ATA 190 is set up in CUCM.  I changed from T.38 Fax relay to the below:
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