Use Microsoft Communication control (MSCOMM32.ocx) to open port with modem atached to it and send command to modem :

MS comm control object name in form is comm

comm.settings='9600,n,8,1'
comm.commport=2 & for modem conected on COM2
comm.openport=.t. & for command to open port COM2
if !comm.openport & test if port opened succesfuly
=messagebox('..... & prompt user for fail command
return
endif
comm.output='ATDT092346626' & to dial the number you want

string for output came from database, text control or any other way

comm.openport=.f. & close port

Commands for modem are listed in modem book.