It would be something like this
description IPphone+PC
switchport trunk encapsulation dot1q
switchport mode trunk
switchport access vlan 2
switchport voice vlan 100
switchport trunk allowed vlan 2,100
spanning-tree portfast
The purpose of the trunk command is to allow the port to use multiple VLAN's. The old 2900 series switches need this setting, newer switches aren't like this.