Cable Modems and ISDN???

["David V. Femia" <davidv@future.dreamscape.com>]

  I am very interested in the issue of cable modems vs. ISDN.
  
  I believe I read recently that cable modems are incapable of video 
  conferencing and voice. Is this entirely true? 
  
  Assuming that it is, and having worked with ISDN with multilink ppp, 
  I have found 128 kps very adequate for both surfing the Internet and 
  downloading larger files. I recently benchmarked a 28.8 analog modem 
  against an ISDN at 128 kps in downloading a 4 MB file. It took 28 
  minutes with the modem and 5 with the ISDN line. This leads me to 
  think that ISDN is not only a near term technology at the ready but 
  may indeed have life after cable modems are deployed, whenever that 
  might be.
  
  Any comments or opinions?
  
  dvf