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SPA112 drops connection working with Fax Server

BRYAN HUNT
Level 1
Level 1

I installed 4 SPA112 units this week for fax machines at a client location.  Three worked perfectly, one fails while executing the fax handshake.

I updated the firmware to 1.3.1 (003), that did not help.

The failing unit is attached to a Fax Server, which is a  Windows XP computer with an older internal Dell Fax/Modem card.  The Fax Server has been functioning perfectly while connected to an analog extension to their old PBX.

All works fine until the receiving fax machine answers and sends its handshake-tones.  Then the fax server hangs up immediately.

This ATA unit is for outbound faxing only, with either a 10 digit or 11 digit (long distance) dial string.

Is there a best practices document that describes suggested settings for optimizing the SPA112 for use with a fax machine?

Thanks.

Bryan Hunt

10 Replies 10

chrebert
Level 4
Level 4

Hello Bryan,

There is a section in the admin guide called Optimizing Fax Completion Rates that goes over the settings changes on the SPA and on the fax machine you can make to make faxing more reliable.

The admin guide is available here:

http://www.cisco.com/en/US/docs/voice_ip_comm/csbpvga/spa100-200/admin_guide/SPA100_AG_OL-25117.pdf

You are looking for page 40.

GIve those settings a try and let me know how it goes.

Christopher Ebert

Network Support Engineer - Cisco Small Business Support Center

Chris,

Thanks for the reply.  I completely missed that in the manual.

I will apply those recommended settings and see if that helps.

I'll report back here on results.

Thanks.

Bryan Hunt

Chris,

I applied those recommended settings and re-tried.  No joy.

I am attaching the log from the failed fax attempt.  Perhaps you may see something in there that indicates why the call gets terminated?

Thanks.

Bryan Hunt

Log you attached is so incomplete, so it can't help.

You should capture all log and debug messages, not only the local0 facility and not only the info severity and above. 

Also, read the

Dan,

Thanks for the information.

I was able to capture a debug syslog of a failed call.

It is attached to the case.

Thanks.

Bryan Hunt

At the first, it seems you are using G711ulaw as the only codec. In such case, there is almost no reason to recognize fax call as speciall call. It is usefull when a compressed codec (like G.729) is used because fax calls needs to be switched to uncompressed codec like G711. You are on G711 already. Of course, it's not reason to hang-up.

So, what I see in your log. Standard INVITE->PROCEEDING->OK sequence, e.g. call setup is completed using G711u code. But then, the PBX's final response '200 OK' si send again and again. ATA device respond 'ACK' to it, but it seems that PBX receive no such ACK.

It the first, veruty that SIP 100REL Enable is set to 'No'. At the second, check Asterisk's console for error messages (raise verbose & debug level on Asterisk). Also, use 'sip set debug ip ...' command and verify that Asterisk got the ACK packet from device.

As last resord, catch the debug/log/sip packets from the other ATAS which has no problem. We can compare both logs then. ALso, compare the configuration of both ATAs (save the current configuration into file, use 'diff' or simmilar tool to catch differences).

Dan,

Thank you for your continuing assistance with this issue.

I checked that ATA and the 'SIP 100Rel Enable' setting has always been set to 'No'.

We have 3 SPA112 ATA's in use for fax machines (today adding a 4th).  2 of them are hooked to 'true' fax machines and work just fine.  The 3rd (the unit we are struggling with) is hooked to a 'fax server', which is a PC with an internal Dell fax/data modem in it.  That card is probably about 10 years old.  It works fine with the old analog circuit connected to their old PBX, but not with the SPA112.  I'm not sure if it is related to the age of the card or the age of the driver?  I have been thinking about trying to dig up an external fax/modem for that machine to see if it is card related.  I have the card set at the COM port level to run at 9600, but not sure if there is any way to prove that it is actually stepped-down to 9600.

I have attached screen shots of the SIP and Line settings.

Can you think of any other settings that we could try?

Thanks.

Bryan Hunt

I'm sorry, I edited my message at the saem time you replied as I got another idea. Please reread it.

If you suspect that problem is related to analog device type, then it's easy to verify the idea. Connect the problematic card to the ATA that is verified to work elsewhere. If problem disappear, then it's related to the ATA device. If problem doesn't disappear, then it's related to analog device.

In the second case, check the configuration. Most important are POTS line parameters like FXS Port Impedance. It need to match analog device settings/requirements. Some card may be more sensitive to it as other, so this card may misinterpret line condition. Well, it may not be the source of problem for sure, but it's hard to guess ...

I have the card set at the COM port level to run at 9600, but not sure if there is any way to prove that it is actually stepped-down to 9600.

Are we speakign about WIndows ? Then it's possible to catch all 'AT' commands sent to the modem. It may reveal the configuration used during the call. But I have no WIndows near me, so I can't tell the exact place to turn the log on. It's somewhere in modem/serial configuration and the log file will be created in \WINDOWS\ directory (if I remember correctly).

Dan,

I'm leaning more towards a physical issue (like impedance) than an issue with the Asterisk server, mainly because the other two ATAs worked perfectly out of the box without any special settings (even the optimized fax settings).  They are all working with the same Asterisk PBX.

That said, tweaking things like impedance and/or gain is stepping out of my realm of experience.

Do you have any recommedations of settings that I should try to see if I can get a better match-up?

Thanks.

Bryan Hunt

Well, the modem in question has been manufactured/vendor-customized for a specific market (country). Most countries in Europe has one typical impedance (and other POTS parameters). I have no experience with US market.

Do you know the country your's fax card has been manufactured/customized for ? Then you should try the impedance that's most common for such country. Also, you noticed the card worked with old PBX - so you can try the same impedance that's used on such PBX.

Don't forget that "impedance problem" is just idea. It's not final answer to your question.

If you know the exact type of your card, then you should found and read it's documentation. Some fax card allow operator to ask for "last hangup cause" using apropriate command. It is another idea that may (or may not) help.

If you can, try PAP2T adapter instead of SPA112. Althougth PAP2T is end-of-sale, the SPA112 can't be considered as reliable replacement for it yet. It's so new and unstable. Of course, even PAP2T may not solve the problem in question ...

I'm sorry, but I have no clear answer for you.

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