Traditionally with Switching, there are two types of ports:
Access Ports -- ports which carry traffic for only one VLAN
Trunk Ports -- ports which carry traffic for multiple VLANs
In a scenario where a user has their PC plugged into the wall. You would typically configure the switchport that user is connected to as an Access Port:
Switch(config)# vlan 22 ...
The access VLAN is what is used for devices, such as PCs, connecting to the switch interface.
VoIP phones can use CDP (or possibly LLDP, depending on the model and switch configuration) to negotiate a trunk with the switch interface, and the phone will use the VoIP VLAN for itself. If you connect a different device to the phone, the phone will act as a ...