User`s manual

U.S. Robotics I-modem Command Reference
Troubleshooting • Page 15-9
¥ Make sure your I-modem's connection rate setting, &Nn, is correct for the call. If the
connection rate is locked at a speed (&N1*&N14) different from the calling modem's,
the I-modem hangs up. The default setting of &N0 (variable link operations) allows the
two modems to negotiate the highest possible connection rate.
¥ If your modem is attempting to answer a V.32 call, you may need to lengthen the extra
V.32 answer tones. See Appendix
A, Alphabetic Command Summary, under S28.
¥ If you are attempting to make a connection using HST modulation, make sure the
modem at the other end of the line is HST-compatible, V.32terbo compatible at 14.4
Kbps, V.32 compatible at 9600 bps, V.22bis-compatible at 2400 bps, Bell 212A-
compatible at 1200 bps, or Bell 103-compatible at 300 bps.
¥ If none of the above corrects the problem, it's likely that the quality of the phone connec-
tion is poor. The variable quality of phone line connections may be due to any number of
conditions in the phone service's equipment or the current environment. Try several
calls, and if you still can't get through, try calling another device. If the second device
accepts your call, the problem may lie with the device you Þrst tried to call.
Errors during software download
Try running the PCSDL program at a lower serial port rate. External I-modems Only: if
your computer doesnÕt have a 16550 UART, a slower serial port rate can make all the dif-
ference.