From the "Macintosh Express Modem User's Guide":
* Preface, page ix - The PowerBook Duo 14.4 Modem and PowerBook 14.4 Modem will not work with party lines, cannot be connected to a coin-operated telephone, and may not work with a digital private exchange (PBX) system.
* Chapter 1, page 4 - To use your Express Modem, you need an ANALOG telephone line. Most hotels and other buildings use an exchange system (PBX) with digital extensions. If the office or hotel room has a digital extension, consult the office telephone manager or telephone service provider to determine if an analog line can be installed.
CAUTION: Be sure to request an analog telephone line, because higher voltage than recommended may cause damage to your Express Modem, and the repair will not be covered under warranty.
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