Oleg,

Ok. Give me a day to dig some up. While you are waiting why not look at this. It generates DTMF using a different technique but may be good reference i haven't tried it. It uses up 2 timers so if DTMF generation was only a small part of what i wanted to do i probably would use this type of technique.

http://www.microshadow.com/english/page8051.htm