Skype and conference calls

I particularly like Skype for listencing to long conference calls,  I find the listening quality excellent, not quite so good for participating, and it’s better than my speaker phone because people can’t hear me typing.  I know it costs a few pence more because there is no freephne support in skype,  but still I like it.  The problem seems to be – isn’t there always a problem – that somewhere in the Skype Out chain the DTMF tones get screwed up and this makes it almost impossible to actually get connected to the call, ie entering your PIN etc.   Other people have had this problem too.