Hi,
i've done a similar project on DTMF remote control system.
Please inform me more details about your project.
I used UMB91214 IC as DTMF code generator and 8870 as DTMF to BCD convertor for my project.
MY circuit was quite similar to one shown below :
(but it used KT3170)
h**p://electronicsworld.tripod.com/remotecontrolsimages/remotecontrolsckt2.html
A number of DTMF Ic's are available in market already.
Please make a search and i don't think it would be a tough job.
You might also find this link useful :
www.geocities.com/constantinescuradu/content/dtmf.htm
See ya !!