We have a telephone device that programs itself with DTMF once connected to it's destination.
It wont work with the Obi110 because the OBI doesnt seem to recognise the digit "C" on the phone port. It does 0-9 A,B,D, * and # ok but not "C"
I know this is not usually an issue as most phones cant generate ABCD, but ours needs to.
Does anyone have any ideas. We are using RFC2833 to a freeswitch server, but that isn't relevant as the obi doesn't generate an event for the digit C
thanks, in advance
That is quite strange.
First, it appears as though all other buttons work.
Touchtones are comprised of two separate tones which are not harmonically related, thus should not generate spurious tones.
Look at the keypad (I assume ABCD are down the right column).
The columns and rows are each a difference frequency. Thus the column for ABC and D share one tone (1633 hertz) and the 789C row share 852 hertz, thus C is 852hz and 1633hz.
Since all other keys in the row and column work except "C" it sound like a bad contact for that key. It is possible that one tone is just a bit low in volume, but that usually effect the other associated keys.
Go here for a complete explanation:
http://en.wikipedia.org/wiki/Touchtone#.23.2C_.2A.2C_A.2C_B.2C_C.2C_and_D
Also, this link will play "C" for you. Does your keypad make that sound?
http://upload.wikimedia.org/wikipedia/commons/9/96/DtmfC.ogg
There is always the case that your "C" key is not triggering both tones and you are only getting 852 or 1633 as a pure tone.
Thanks for your thoughtful reply, but im afraid the problem would appear to be in the OBI's detection software.
We have proved our equipment is generating the right tones by connecting it to different equipment and also looking at the spectrum and frequencies generated. For example a linksys ata has no trouble with all the digits.
Also we have connected different devices that can generate all digits using hardware and they fail on the OBI.
We are pretty convinced that there must be a bug in the obi dtmf algorithms.
I did wonder if OBI might be using the 'C' digit for something special.
You may be right, they may have missed a comma or closing bracket somewhere.
In a large computer company I was asked why the search for data in a large database took forever. Turns out they were looking sequentially for the first match, but forgot to exit the search when they found the answer. Thus they kept looking even though they had the answer.