Oce 3121 Technical & Service Manual page 162

bit 6: 1 To transmit a 1850-Hz tone signal, when bit 5 is set to 1.
0 To transmit a 1650-Hz tone signal, when bit 5 is set to 1.
bit 7: 1 To transmit a tone signal, before sending a CED signal.
0 Not to transmit a tone signal, before sending a CED signal.
54 TSM Océ 3121/3122 FAX related error codes