Cisco Catalyst 3560 and 802.1Q VoIP
Some VoiP devices require the use of 802.1Q, encapsulation protocol, to set this up you are going to have to do this using telnet, and on a per port basis.
If you don’t know how to start a telnet session with your Cisco device, then I suggest you stop reading now, and defer this task to someone who does, no offense but getting this wrong can screw up your network.
User Access Verification Password: 3560>enable Password: 3560#conf t Enter configuration commands, one per line. End with CNTL/Z. 3560(config)#int GigabitEthernet0/1 3560(config-if)#switchport trunk encapsulation dot1q 3560(config-if)#switchport mode trunk 3560(config-if)#^Z 3560#wr mem Building configuration... [OK]
All you need to know is above, simple rinse and repeat for the other ports you wish to use 802.1Q, of course you can forgo the CTRL+Z followed my wr mem if you have multiple ports to do, just make sure you do CTRL+Z folowed by a “wr mem” otherwise your changes will only effect the current running configuration, if the device is restarted for whatever reason changes will be lost.