A method of controlling a re-dial operation of a calling facsimile system upon occurrence of an error in attempting a non-standard facsimile capability transmission between the calling facsimile system and a called facsimile system connected therewith via a public switched telephone network, comprising:
- in response to a call received by a called facsimile system from a calling facsimile system dialing said called facsimile system, detecting whether a non-standard setup command is received by said called facsimile from said calling facsimile system;
- upon detecting that no non-standard setup command was received by said called facsimile system from said calling facsimile system, setting a normal transmission and reception flag in said called facsimile system;
- detecting whether a non-standard facilities command is received by said calling facsimile system from said called facsimile system;
- upon detecting that no non-standard facilities command was received by said calling facsimile system from said called facsimile system, setting a normal transmission and reception flag in said calling facsimile system;
- upon detecting that a non-standard setup command was received by said called facsimile from said calling facsimile system, setting a non-standard facilities capability information in a non-standard facilities information field of said called facsimile system for informing said calling facsimile system that said called facsimile system retains any non-standard capability and transmitting a non-standard facilities command containing said non-standard facilities information field from the called facsimile system tot he calling facsimile system;
- upon detecting that a non-standard facilities command was received by said calling facsimile system from said called facsimile system, setting a specific non-standard capability which will receive service into an information field of a non-standard setup command of said calling facsimile system and transmitting said non-standard setup command from said calling facsimile system to said called facsimile system for requesting servicing of said non-standard capability by said called facsimile system;
- upon receiving said non-standard setup command from said calling facsimile system, analyzing said information field of said received non-standard setup command and determining whether any non-standard capability corresponding thereto requested by said calling facsimile system is serviceable by said called facsimile system;
- upon receiving said non-standard facilities command from said called facsimile system, analyzing said information field of said non-standard facilities command received by said calling facsimile system and determining whether any non-standard capability corresponding thereto requested by said called facsimile system is serviceable by said calling facsimile system;
- upon determining that any non-standard capability requested by said calling facsimile system is serviceable by said called facsimile system, setting a non-standard capability transmission and reception flag in said called facsimile system for causing said called facsimile system to perform said requested non-standard capability;
- upon determining that any non-standard capability requested by said called facsimile system is serviceable by said calling facsimile system, setting a non-standard capability transmission and reception flag in said calling facsimile system for causing said calling facsimile system to perform said requested non-standard capability;
- upon determining that any non-standard capability requested by said calling facsimile system is not serviceable by said called facsimile system, setting an error flag in said calling facsimile system and terminating communication with said called facsimile system;
- and
- upon re-trying further facsimile operation by said calling facsimile system, detecting whether an error flag has been set for thereby preventing any re-dialing by the calling facsimile system of the called facsimile system.