For the voice over IP lab, you need the following equipment:
Two Cisco voice-capable routers, each with an FXS interface where you will connect your analog phone sets. We used Cisco 3600s in our labs, but the Cisco 2600s will work nicely as well.
A low-end Cisco router, such as a Cisco 2500 series (something with two serial interfaces), that you will use as your Frame Relay switch.
Two analog phone sets.
Physical Layout and Prestaging
Connect one of the Cisco voice-capable routers to the Serial 1/2 interface on the Cisco 2600 series router (Frame switch), as shown in Figure 6-27.
Connect the other Cisco voice-capable router to the Serial 1/3 interface on the Cisco 2600 series router (Frame switch), as shown in Figure 6-27.
Connect an analog phone set to each of the FXS interfaces on the Cisco voice-capable routers, as shown in Figure 6-27.