SIP phone with dual ethernet ports (?)

I need some explanation how it works:

When a sip phone has two ethernet ports, I assume that one port will be connected to a pc and the other port to the network (router).

But, how do the pc and the sip phone get their (dhcp) address when they are both connected to the same router port?

Can I give the pc and the router a fixed address ?


Normally if they have 2 ethernet ports, they have a ‘switch’ or ‘hub’ built in and just pass data.

Therefore DHCP requests will be passed to any device connected through the phone.