Cisco Systems 1700 manual Hardware Installation Guide that comes with every card, NT1

Chapter 1 Cisco 1700 Router Overview

Equipment	When You Use It
Cisco WAN interface card	In order to make a WAN connection, the Cisco 1700 router must
	have a supported WAN interface card installed. The router
	supports up to two cards. You can order the cards when ordering
	the router, and they will be installed for you. You can order the
	cards separately, after receiving the router, and install them
	yourself.
Straight-through	This cable connects the router to the Ethernet LAN and the
RJ-45-to-RJ-45 cable	WAN interface cards to various WAN services, including ISDN,
	T1/FT1, and 56-kbps services. You will need one cable for each
	connection that requires this cable type.
Serial cable	This cable connects a serial card to serial services. You must
	order this cable from Cisco. For detailed information about
	serial cable types, refer to the Cisco WAN Interface Cards
	Hardware Installation Guide that comes with every card.
NT1	Some ISDN service providers require a Network Termination 1
	device to connect an ISDN S/T port to the ISDN line.
Asynchronous modem	Connect a modem to the AUX port on the router when you want
	to configure the router from a remote location.

	Cisco 1700 Router Hardware Installation Guide
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