led, will open a line on every phone configured to receive the call. The call will open a line, enable the speaker, and allow the caller to address the group. Multiple groups can be configured, though here I'll just configure one that will page every phone. All we need to do is create an ephone-DN, but we need to incorporate the special paging ip command. This command allows us to configure a multicast address and port that will be used for paging. Here, I'll configure the system for paging when the number 555 is dialed: R1-PBX(config)#ephone-dn 20 R1-PBX(config-ephone-dn)#number 555 R1-PBX(config-ephone-dn)#description Page All Phones R1-PBX(config-ephone-dn)#paging ip 239.1.1.10 port 2000 You'll see in the next section how to configure the phones to listen for this paging group. Ephone Now that we have our extensions and incoming line configured, we need to configure the phones themselves. We do this with the ephone command. As with the ephone-dr command, we need to specify an ephone descriptor-a description helps to keep all the phones straight: 1-PBX(config)#ephone 1 R1-PBX(config-ephone)#description GAD Chapter 30: VolP Phones are referenced by their MAC addresses, which can be found on a sticker on the bottom of Cisco IP phones. Feel free to use your networking skills to learn the MAC address through other means: R1-PBX(config-ephone) #mac-address 0019.AA96.D096 To make this phone part of the paging group we created earlier, we'll use the paging- dn command, followed by the DN numbered we created: R1-PBX(config-ephone)#paging-dn 20 By configuring the phone type, the system will know which firmware files to serve it when it registers: R1-PBX(config-ephone)#type 7971 Now it's time to configure the phone's buttons. In its simplest form, you specify the button number and pair it with an ephone-DN. Thus, 1:1 will attach the extension configured in ephone-DN 1 to button number 1 on the phone. The buttons are num- bered from the top down. The phone model you're using will dictate how many buttons you can configure