asterisk users - Apr 2008 - zaptel_vldtmf

Hi.

I am trying to install "asterisk_srtp".
I started by installing zaptel-1.4.9.2 and then I run the configure of  
asterisk_srtp. In the menuselect of asterisk, the chan_zap in "Channel  
Drivers" is always unselected(XXX). The only dependency that I don't  
seem to have is zaptel_vldtmf.
Where can I find this zaptel_vldtmf? If I understod correctly, zaptel  
1.4 should already have this.

Thanks