Characteristics and Protocols for Terminals for Telematic Services in ISDN - Amendment 3: Cause Value for a G4 Fax Fall-Back - Series T: Terminals for Telematic Services Study Group 8; 7 pp
Most G4 facsimile provides fall-back function from G4-mode to G3-mode. When the call with G4-mode is disconnected with pre-defined cause values, of ISDN service, G4 facsimile tries to make the second call with G3-mode automatically.