Cisco 870 Series

4-14
Cisco 850 Series and Cisco 870 Series Access Routers Hardware Installation Guide
OL-5331-01
Chapter 4 Router Cabling Procedures
Connecting an ISDN S/T Port
Perform the following steps to connect the console port on the router to an async modem:
Step 1 Connect the RJ-45 end of the router modem cable to the console port.
Step 2 Connect the DB-25 connector end of the router modem cable to an available port on the async modem.
Step 3 Connect one end of the RJ-11 telephone cable to a wall jack, and then connect the other end of the RJ-11
cable to the modem.
Step 4 (Optional) Connect one end of an RJ-11 telephone cable to a telephone, fax, or other device, and then
connect the other end of the RJ-11 cable to the modem.
Connecting an ISDN S/T Port
This section applies to Cisco 876 and Cisco 878 routers. You can connect the ISDN S/T port to the ISDN
service provider as a backup link to the WAN port in case the ADSL service goes down.
The cabling requirements and information for the ISDN S/T connection follow:
• You must provide two unshielded Category 5 cables. The first cable connects the NT1 box to the
splitter, and the second cable connects the splitter to the wall jack.
• There are RJ-45 connectors at both ends of the default orange ISDN S/T cable. However, an
RJ-45-to-RJ-11 ISDN S/T cable is available upon request if the wall jack at the site requires an
RJ-11 connector. Contact your router reseller for the appropriate cable.
Caution Both LAN and WAN ports can use RJ-45 connectors. Use caution when connecting cables to these
connectors. To avoid damage to the router, do not connect telephone-network voltage (TNV) circuits
(such as ISDN or DSL circuits) to safety extra-low voltage (SELV) circuits (such as LAN circuits).
Although Figure 4-11 shows an ISDN S/T connection for a Cisco 876 router, this connection also applies
to a Cisco 878 router.