3.2. Fax Terminology

To understand how the fax API functions apply to sending and receiving fax documents, you should understand the distinction among the following terms.

Term	Definition
caller	An application or station that places a call. Also referred to as a calling application or station.
called	An application or station that receives a call.
fax transmitter	An application or station that sends or is capable of sending a fax document.
fax receiver	An application or station that receives or is capable of receiving a fax document.
fax session	The five phases of a fax call as defined by the ITU-T T.30 protocol recommendation. They are:   Phase A (set up fax call)   Phase B (pre-message procedure)   Phase C (transmit message)   Phase D (post-message procedure)   Phase E (release fax call).
normal transmission	A type of fax transmission where the caller station transmits a fax to the called station.
polling transmission	A type of fax transmission where the called station is asked (polled) to transmit a fax back to the caller station. Also referred to as polled transmission.
turnaround polling transmission	A type of fax transmission where the caller and called stations alternate between transmit and receive modes during the same call.

The fax library allows your fax application to be a caller or called application, and a fax transmitter or fax receiver. This distinction is important in a polling transmission where the called application transmits documents back to the caller. Polling transmission is described in detail later in this chapter.

NOTE:

The discussion of fax transmission and reception in this chapter is based on the use of the fax application as both a caller and called application. Your fax application will be either the caller or the called application. The other station (the remote station) may be a fax machine or another fax application.

As a fax transmitter, your application can perform the following fax procedures:

• Send a complete fax document or send data from various sources with independently defined page and document boundaries.
• Send an indication to the receiver requesting the receiver to send a fax document to the transmitter (polling).
• Both of the above during the same call.

As a fax receiver, your application can perform the following fax procedures:

• Receive incoming fax data.
• Indicate to the transmitter if polling is acceptable.
• Indicate to the caller that the called application only has fax transmission capabilities (caller can only receive a fax or disconnect).

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