I got a call today from the exact same number but the guys name is Sam Wise. Who are these people and I would appreciate if they tell what company they work for.

2013-04-19 - Same thing. Calls and leaves an aggressive sounding voice message.
"Yeah, this is Jim Maxwell. It's very important that you contact me back at 888-638-8704."

Call came from 415-578-0998.

Right - Like I'm going to call someone who doesn't even tell me:
* WHAT COMPANY he's calling from.
* Let alone what it's about in the first place.

Again, the individual was JIM MAXWELL this time.
(Hi Jim. It's very important that you stop calling.)