I've pulled some of the material from the CD-ROM and created ZIP files for those who wish to download them. What's available from here are copies of the book's source code examples, some shared system-level files, and the major projects for each section of the book. This includes the TAPILINE application which can be found in the TAPI ZIP set here.
The book has been out of rpint for several years. In fact, it never really sold all that well. However, once it went out of print, requests for it continued. It turns out at least one server keeps a copy of the entire text of the book available on the web. If you wish, you can check it out at the URL below. I have nothing to do with the site and don't know the folks involved. However, if you find the hosted contents valiable, I encourage you to let the site hosts know. They could probably use the encouragement!
For those who just have to own this book, you can probably find a used copy through EBay, Amazon.com, or other onelin resellers.
Probably the #1 resource for TAPI-related info is Burce Pennypacker's "My unofficial TAPI FAQ" Bruce was a valiable resource for TAPI items in the past and his pages are still commonly referenced even today. If you have questions about TAPI, his site might have the answer.
There is a Microsoft-hosted newsgroup forum for TAPI: microsoft.public.win32.programmer.tapi. I can't vouch for the content and I don't hang out there anymore, but it might be another source for you to check out.