2.2 Programming
Programming Guide
23
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
•
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
