mute while recording a call?

[superman651]

I attend these weekly seminars that also provide for you to call in over the phone to listen if your unable to attend. I wanted to use this feature with my "in call recording" feature on my TP2 to record them and save them for later. Although when I attend and record the seminar through my phone, I get the speakers voice over the sound system so there is an echo and quite annoying. I tried using the mute feature thinking it wouldn't record anything through my phones microphone but it doesn't seem to work. Any ideas on how to record a phone call but not to have it record your own voice?