Yes, equal is correct I have several of these adapters I use with AppleTalk and they work flawlessly, however, they do not work with any modems I have tried, which otherwise work well with the dedicated modem cable. With the pin-out information, you should be able to construct your own. SOme of these links may help too:

http://docs.info.apple.com/article.html?artnum=170

http://docs.info.apple.com/article.html?artnum=1762

http://docs.info.apple.com/article.html?artnum=12943

http://docs.info.apple.com/article.html?artnum=1780

http://docs.info.apple.com/article.html?artnum=7757