Regarding recent discussion of the "serial port is busy" problem with Global Village modems on PowerBooks, Derek Briton reminded me of the following additional possible solution, previously posted on O'Grady's PowerPage:
"A contact at Apple found a more reliable work-around for the Global Village/Open Transport PPP bug:
1. Switch TCP/IP to something that doesn't use the modem, such as MacIP or Ethernet
2. Trash ASLM preferences
4. Switch your TCP/IP settings back to what they were"