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#81722 by aznillini
Thu May 19, 2011 8:48 pm
Hello,

I have been trying to fax documents with my All-In-One Canon MX870 Printer. I have been unsuccessful. I have read all the forum questions and answers regarding fax setup and tried everything: reducing baud to 9600, turning off ECM, tried dialing *99 in front of the fax number, enabled fax from the my.ooma.com page, directly connected fax machine to Telo, etc.

Nothing will work.

Does anyone have any suggestions as how I can get Ooma to allow me to fax??????

Any help would greatly be appreciated. Thanks!

A Frustrated OOMA User
#81730 by tomcat
Fri May 20, 2011 5:08 am
I have seen suggestions to add a pause (sometimes two pauses) between the *99 and the number being dialed. Sometimes this has worked for users and other time it hasn't. Hope this works for you.
#81772 by daet
Fri May 20, 2011 12:37 pm
You could try putting a DSL filter in opposite orientation between the fax machine and the Telo. Unlike voice, fax transmission is highly timing dependent. So a QoS that is adequate for voice can be sufficient to stop a fax transmission from working.

DG
#81781 by nn5i
Fri May 20, 2011 2:02 pm
daet wrote:You could try putting a DSL filter in opposite orientation between the fax machine and the Telo. Unlike voice, fax transmission is highly timing dependent. So a QoS that is adequate for voice can be sufficient to stop a fax transmission from working.

DG

I find it intriguing that several people recommend this, and most say to connect it backward. That's nonsense. It is a nearly symmetrical low-pass filter, though C-input one way and L-input the other; and as a filter it will work about equally well in either direction. Turning it backward, however, does change the input impedance by placing a capacitor directly across the incoming phone line -- not a good thing. If you use a DSL filter where there are no DSL signals to block, it won't do much harm (though it also won't accomplish anything good, either). But if you turn it backward, presenting Ooma with a capacitor-input low-pass filter instead of an inductance-input lowpass filter, you may possibly degrade the performance of the Ooma device by presenting, at certain frequencies, a very low shunt impedance at its PHONE output. This could degrade Ooma's audio performance, and possibly its ringing performance.

So where did that recommendation come from? Someone, not an engineer, pulled it out of -- out of -- well, let us say out of thin air, and others repeated it. This allows them to feel the pride of a creator, simply by performing the feat of a parrot.
#81795 by tegelad
Fri May 20, 2011 5:01 pm
When you connected the fax machine ... how do you have your phone "topology"?

E.g. on my setup, I was able to run with the default settings on a Canon Faxphone L80; however, I only plugged the Fax machine into the phone jack on the back of the telo, and I use only the telo handsets/bluetooth adapter for my calls.

Secondly, I went and seperated the two phone numbers I have on the telo and put one on the telo handsets and one on the fax machine, and enabled the fax mode on the line (and) always dial *99 .... and 90%+ of the time I am successful...

+-ADT
aznillini wrote:Hello,

I have been trying to fax documents with my All-In-One Canon MX870 Printer. I have been unsuccessful. I have read all the forum questions and answers regarding fax setup and tried everything: reducing baud to 9600, turning off ECM, tried dialing *99 in front of the fax number, enabled fax from the my.ooma.com page, directly connected fax machine to Telo, etc.

Nothing will work.

Does anyone have any suggestions as how I can get Ooma to allow me to fax??????

Any help would greatly be appreciated. Thanks!

A Frustrated OOMA User
#81874 by daet
Sun May 22, 2011 7:04 am
I don't know how it works, but have no doubt that it works. With a DSL filter in place - pigtail into the fax machine (MFC 7820N), I can reliably send multi-page faxes at 33600 bps, with error-correction on, and in resolutions as high photo mode.

Without the DSL filter in place, I can reliably send faxes at 9600 bps, with error-correction turned off, and at standard resolution. Occasionally, I have been able to send a fax at 14400 bps.

While I have no idea how it works, my experience with this "solution" is not unique. A Google search for "voip dsl filter fax" or various permutations of those terms provide hits that are redolent of instances of successful fax transmissions with the filter in place (and the pig-tail end plugged into the fax machine).

DG

P.S. Do you often find condescension necessary to be heard?

nn5i wrote:I find it intriguing that several people recommend this, and most say to connect it backward. That's nonsense. It is a nearly symmetrical low-pass filter, though C-input one way and L-input the other; and as a filter it will work about equally well in either direction. Turning it backward, however, does change the input impedance by placing a capacitor directly across the incoming phone line -- not a good thing. If you use a DSL filter where there are no DSL signals to block, it won't do much harm (though it also won't accomplish anything good, either). But if you turn it backward, presenting Ooma with a capacitor-input low-pass filter instead of an inductance-input lowpass filter, you may possibly degrade the performance of the Ooma device by presenting, at certain frequencies, a very low shunt impedance at its PHONE output. This could degrade Ooma's audio performance, and possibly its ringing performance.

So where did that recommendation come from? Someone, not an engineer, pulled it out of -- out of -- well, let us say out of thin air, and others repeated it. This allows them to feel the pride of a creator, simply by performing the feat of a parrot.
#81878 by nn5i
Sun May 22, 2011 8:34 am
daet wrote:Do you often find condescension necessary to be heard?

No, not often, only sometimes. On those occasions it's very natural.
#81890 by daet
Sun May 22, 2011 11:50 am
It is a sadness for it to take the place of reason.

DG
P.S. If you search relatively carefully, you'll find a rationale from Packet8 and Vonage as to how a DSL filter likely helps.
nn5i wrote:No, not often, only sometimes. On those occasions it's very natural.
#81894 by nn5i
Sun May 22, 2011 12:53 pm
daet wrote:It is a sadness for it to take the place of reason.

DG
P.S. If you search relatively carefully, you'll find a rationale from Packet8 and Vonage as to how a DSL filter likely helps.
nn5i wrote:No, not often, only sometimes. On those occasions it's very natural.

True. This also is true of confirmation bias, of which I think this thread and others offer examples. Anything, substituted for reason, is unfortunate. Fortunately, it is possible -- instead of substituting -- for these things to exist in addition to reason. I believe that was the case with my post, in which I don't deny the existence of sardonicism -- I deny only that sardonicism was the only thing there. I did, after all, examine the schematic of a standard DSL filter and analyze how it worked and what it could and couldn't do. I don't think anyone else in this discussion has done that, and I have no reason to suppose that any of them could do that. Thus my scorn for what I see as pretended knowledge.

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