Originally Posted by
Santander
Try following TB 99 for fax on VOIP. I have not run into a VOIP implementation that I could not get to work, though sometimes very slowly. First step, never turn off ECM. If a packet is dropped and ECM is OFF the machine cannot request a resend resulting in a failed transmission. One of the biggest problems with fax on VOIP is the loss of packets which interrupts the critical fax timing. Fax being designed for an analog phone system has very explicit timing requirements which if not followed result in a failed transmission/reception. I have had to change incoming and outgoing DB levels and even the echo timing to get some to work. The lowest baud rate I have had to set was 9600. As for your second question, Kyo units from the early 90's had an encryption mode built into the fax system. The user selects the encryption key, securely sends it to the receiving user who enters it into their machine then all communications between the units is encrypted, works quite well. Have a few drug enforcement units using it. They have a network wide encryption key and encryption keys for individual locations and headquarters, prevents someone from tapping a fax line and recording the transmission and then playing it back to a fax to see the transmission because the encryption key exchange is interactive and without the proper response the key is considered not valid.
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