Cisco documentation stated this:
When you enable port security on an interface that is also configured with a voice VLAN, you must set the maximum allowed secure addresses on the port to two plus the maximum number of secure addresses allowed on the access VLAN. When the port is connected to a Cisco IP Phone, the phone requires up to two MAC addresses. The phone address is learned on the voice VLAN and might also be learned on the access VLAN. Connecting a PC to the phone requires additional MAC addresses.
So we would need 3 MAC addresses for a simple IP Phone <-> PC connection according to this. The phone would need 1 MAC for Voice, and 1 for the MAC for Access? Any clarifications on this, thanks.