After 3 days of morning soldering, got the dtmf decoder with isolation transformer circuit working, The calls can be recorded to PC. I discovered a freeware voice recorder with silence detection called mega voice recorder available at http://www.globalsoftware.biz/

Now the remaining portions are

  1. Off hook Detector (I need parallel off hook with optical isolation)
  2. Ring Detector – for differentiating incoming and outgoing digits.
  3. PIC Micro for processing
  4. RS232 line driver
  5. EEProm storage
  6. RTC

Once I start with PIC I think I’ll be back with a newversion of jaledit with JALV2.