Dell 3115cn Service Manual page 56

Each phase is detailed below:
Phase A - Call Establishment
In order for a fax call to be established, both ends of the line must recognize that the other end is a
non-voice (fax) terminal. Since G3 fax communication is intended for a transmission over the con-
ventional voice network, a fax communication must be initiated via audible tones.
The sending side sends out a Calling Tone (CNG.1100Hz for 0.5 sec.), which identifies itself as a
fax terminal. Then, the receiving side responds with a Called Station Identification (CED. 2100Hz for
3 sec.) to identify itself as an available fax terminal. Thus, a fax call is established between the two
terminals.
Phase B - Capability Negotiations
The receiving side presents all of the capabilities it has to offer by sending out NSF/CSI/DIS signals.
Then, the sending side responds with NSS/TSI/DSC signals to declare what it has selected from the
capabilities presented by the receiving side.
The sending side sends out a training signal (TCF) to adjust the modem to the maximum transmis-
sion rate available. Upon a successful reception of TCF, the receiving side responds with CFR,
which indicates that the receiving side is ready for receiving image data. In the event of an anoma-
lous TCF reception, the receiving side responds with FTT, which requests retransmission of NSS/
TSI/DCS and TCF signals.
Phase C - Image Data Transfer
The sending side transmits the image data based on the parameters agreed upon in Phase B. Also
carried out are the signaling control procedures including synchronization, error detection/correc-
tion, and line supervision.
Phase D - Post-transfer Procedure
In the post-transfer procedure, the sending side checks its status after the completion of Phase C
and sends an appropriate signal to return the session to the previous phases. When there are more
pages to follow, the sending side sends out MPS and the session returns to Phase C. When there
are more pages to follow and the subsequent page is to be sent in a different mode, the sending
side sends out EOM and the session returns to Phase B. The session proceeds to Phase E only
when the receiving side receives EOP indicating that the sending side has completed transmission
of the entire document. Therefore, the session may show a looped sequence such as ABCDCD . . .
E, ABCDBCDBCD . . . E, etc., depending on the remainder of the document or the transmission
parameters for the subsequent page.
Version 1 2006.11.21
Chapter 1 Troubleshooting