ISDN is offered over a specially installed telephone line. It is possible to initiate or receive telephone calls or faxes while accessing the Internet. However, the speed of the Internet connection will fall by 50% during a concurrent telephone call or fax:

• Integrated Services Digital Network
• older technology, combines two 64 kb/sec channels (128 kb/sec)
• basic phone service is included
• $55/mo., user must purchase modem
• usually limited to 100 hours/mo. usage before an additional hourly charge is applied