| 摘要 |
Gracefully forcing two V.34 fax devices to use legacy G3 modulations (e,g., V.21, V.27ter, V.29, V.17) when communicating over a packet network (e.g, voice over Internet Protocol (VoIP)network). To force an originating fax terminal 10 and receiving fax terminal 18 to fallback to legacy modulation procedures, transmission of a Call Menu (CM) "FAX" signal 54 transmitted by the originating fax device 10 is suppressed S 38 at either the originating VoIP/FoIP gateway 12 or answering VoIP/FoIP gateway 16 . The suppression of the CM signal 54 forces the answering V.34 fax device 18 to timeout and fallback to non-V.34 fax modulations S 40 as if the calling terminal 10 was not V.34-capable. Likewise, upon detecting the non-V.34 fax signals, the originating V.34 fax device 10 will fallback to non-V.34 fax procedures S 42 . The two V.34 fax terminals will continue the fax transmission using non-V.34 modulations S 44.
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