Gigabit switch router

[compo_41]

I have lynex router with 4 ports on 100mb. I am running out of ports since installing my voip phone. what is the best way to extend my ports and who sells the gadget device I need

 

[compo_41]

I have zyzel router with 4 ports on 100mb. I am running out of ports since installing my voip phone. what is the best way to extend my ports and who sells the gadget device I need