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2.2 Programming
24 Programming Guide
FAX High Reliable Method
If ECM-capable fax machines are not available, it is necessary to use the "FAX High Reliable
Method" (a proprietary feature of the card). This feature is used to multiplex the packets when
sending them over the network for protection against packet loss. Hence it is possible to achieve
reliable fax communications without using ECM-capable fax machines.
However, keep in mind that this feature does not entirely guarantee error-free fax communications.
Also, more bandwidth is required for one VoIP channel when using this feature. The tables below
show the amount of bandwidth required for one VoIP channel when this feature is in use and not in
use:
Required Bandwidth for Fax Communication via LAN
Required Bandwidth for Fax Communication via WAN (PPP: Point-to-Point Protocol)
Notes
• To carry out fax communications between the KX-TDA5480/KX-TDA0484 and KX-TDA0490
VoIP Gateway Cards, it is necessary to disable the "FAX High Reliable Method" for the KX-
TDA5480/KX-TDA0484 card.
• Fax communications cannot take place between the KX-TDA5480/KX-TDA0484 and KX-
TDA0480 VoIP Gateway Cards.
• Fax communications in the Super G3 mode are not guaranteed.
FAX High Reliable Method
G.711 Packet Sending Interval
20 ms 30 ms 40 ms
Don't Use 87.2 kbps 79.5 kbps 75.6 kbps
Use 224.8 kbps 213.9 kbps 208.4 kbps
FAX High Reliable Method
G.711 Packet Sending Interval
20 ms 30 ms 40 ms
Don't Use 84 kbps 77.3 kbps 74 kbps
Use 221.6 kbps 211.7 kbps 206.8 kbps