If you have end-of-call tones on your line, check you have turned on the "Enable end-of-call tone detection during playback" option using the "End-Of-Call Detection" settings from the Advanced Telephony Settings button on the General tab of the Settings menu.
If you are in doubt about whether Dial Dictate will do what you want we recommend you try the free download. Seeing the program in front of you often answers most questions