Can I split off my internet and phone modem?

Episode 1114 (2:10:24)

Jim from Woodland Hills, CA
Modem

Jim wants to buy his own modem and send back his Time Warner modem. But they say he has to keep it because of his telephone service. Leo says that may be true, since cable phone service uses VoiceOver IP and the cable modem box may require it. So if he is going to use his own modem for internet, then he'll need a splitter to divide the internet traffic. And that's why Leo hates cable monopolies. His only choice is his cable company. He'll get about 1-2 Mbps with Netflix at best. And that likely means a downgraded quality of Netflix.