Yeah, you need 4 remotes to play the mode where the Wii-mote acts as a phone. I really prefer the normal deathmatch and team deathmatch modes over that one though, but it's fun for a change of pace.
To be honest, I think Red Steel's multiplayer is extremely lacking. There are only 4 levels, few different guns and it could use a huge makeover. That said, I have a ton of fun playing it and I can't wait until we see some multiplayer based FPS, for Wii of course, hit the market.