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Re: [hylafax-users] Is DID required for this application?



On 2005.02.23 11:12 "Donald, Adam" wrote:
Lee



I have enabled tracing as you specified, and sent the log that
contains the
HDLC errors and the tracing information.

I appreciate your help with this!  Please let me know if there is
anything
else that I can provide.

Donald,


HylaFAX isn't at fault here (unfortunately - because now I can't fix this for you).

In ECM data there are "synchronization" sequences that, in the case that I illustrate here should appear as repeating "7E" bytes, however, in the blocks where you see "Bad HDLC terminating flag received" show up the training sequences contain "injected" "FF" bytes. Notice:

... 7E 7E 7E FF 7E 7E ...

That "FF" doesn't belong there, and I can't tell you how it got there, either. The same thing happens in those blocks in the raw (unframed) ECM data (after the synchronization). Raw ECM data should not have "FF" bytes in it. But yet, they appear (here two in a row):

... 04 77 2B 64 C8 FF FF 67 50 D1 13 ...

And every time they do appear they mess the ECM data up, which causes multiple transmissions of the data until one gets through unscathed.

Either the modem is producing them, or your PBX is. Since you can't really reproduce the problem without the PBX I really don't have any suggestions on how to debug it, either, to know which is which. Do you have a different Class 1 modem that supports voice availble to test with? If it happens with a different modem (not a MultiTech) then you can blame the PBX. If it doesn't happen with a different modem, then you can blame this modem, and MultiTech should be able to help you.

I honestly couldn't tell you why this only happens when you use SHIELDED_DTMF, either.

Lee.

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