he 7970s do, the light blinks amber when the line rings. If the other phone has the line seized, the button glows red. When the button is configured as a monitor button, the line does not ring when a call comes in. The button glows red as soon as the other phone goes off-hook on the line. The display screen will also react as appropriate for other events. For example, if there is a voicemail message waiting for the extension, an envelope will appear on the display next to the line's button on each phone. Here's an example. Extension 101 is my line. When someone calls that extension, my phone will ring, but the other phones (set to monitor this extension) will not. They will display an indication that my line is ringing, though. I'm going to configure the main line on each phone as a standard button. I'll then monitor the other lines and add a final button for the general line and mailbox. Here's how I'll assign the buttons on my phone: R1-PBX(config-ephone) #button 1:1 2m2 3m3 4m4 5:10 This will configure the phone buttons as shown in Figure 30-4. The system will not allow you to assign the same DN to two buttons. Here I try to assign DN 3 to buttons 1 and 4: R1-PBX(config-ephone)#but ton 1:3 4m3 duplicate dn [3] assignment: button 4, only button 1:3 accepted Following this scheme, here are the configurations for the four phones in our small office: Phone 1 ephone 1 description GAD mac-address 0019.AA96.D096 paging-dn 20 type 7971 button 1:1 2m2 3m3 4m4 5:10 Chapter 30: VolP Phone 2 ephone 2 description Lauren mac-address 001D.4595.7FE5 paging-dn 20 type 7970 button 1:2 2m1 3m3 4m4 5:10 Phone 3 ephone 3 description Meghan mac-address 0012.4362.C4D2 paging-dn 20 type 7960 button 1:3 2m1 3m2 4m4 5:10 Phone 4 ephone 4 description Colleen mac-address 000D.BC50.FC2C paging-dn 20 type 7960 button 1:4 2m1 3m2 4m3 5:10 Each phone will ring for its primary assigned extension, and will also ring for incoming calls on the POTS line (button 5, linked to ephone-DN 10). If you've got Cisco wireless IP phones such as the Cisco 