7921G, you can configure the Push To Talk (PTT) button to initiate paging. Remember that we've got a paging-DN already set up. Here it is for review: ephone-dn 20 number 555 no-reg primary description Page All Phones paging ip 239.1.1.10 port 2000 Paging works with this configuration, but only when 555 is dialed. To get PTT working on the 7921G, we'll need to assign a button to a new DN, which will then reference the paging DN. It's a bit convoluted, but I didn't write the code, SO you can't blame me. First, we need to create another ephone-DN that references the paging-DN. This DN will use the intercom command, which in our case means, "When 556 is dialed, dial 555": R1-PBX(config)#ephone-dn - 21 R1-PBX(config-ephone-dn)# number 556 R1-PBX(config-ephone-dn)# name IP-Paging R1-PBX(config-ephone-dn)# intercom 555 label "PTT Paging" Small-Office VolP Example To make the button work on the Cisco 7921G, we need to use XML to configure the phone's PTT feature. We do this with the service phone thumbButton1 command in the telephony-services section. Here I'm basically telling the phone, "When I push the PTT button, dial the DN assigned to button 6": 1-PBX(config)#telephony-service R1-PBX(config-telephony)#service phone thumbButton1 PTTH6 This method configures the phone SO that the PTT button is assigned to button 6. If you have multiple 7921G phones and you do not want this behavior on all of them, see the Cisco documentation for alternative methods. Finally, you'll need to assign button 6 (referenced in the preceding code as PTTH6) to ephone-DN 21: R1-PBX(config)#ephone 2 R1-PBX(config-ephone)#button 6:21 Message waiting lamps Though we're not configuring voicemail in this chapter, it's installed, SO we need to configure the phones to interact with the AIM-CUE. One of the must-have features of voicemail is called MWI, short for Message Waiting Indicator. MWI works with ephone-DNs. Unity Express dials a configured number appended with the extension to enable the message lamp. It then dials another configured num- ber,