Have you verified that your controller actually transmits what you had in mind? I mean, if you replace your modem by a pc with terminal emulator, do you see the commmands appearing on the screen? (provided you got the cabling right).

Also check this thread:
http://www.8052.com/forum/rea...&top=60930


If you can dial the number from hyperterminal, and your controller cannot, then your controller has a different behavior than your PC+hyperterminal. Check differences in cabling, output and modem signals. Eventually use a PC as data-monitor to verify transmission between modem and controller.

Also verify DCE-DTE functionality. Your controller MUST behave as a DTE as your modem is a DCE. In that case a null-modem cable should not be used (ie no cross-linked cable!).

regards
Patrick