I used to answer all calls no matter what the I.D. number was. In my experience, all calls from “Unknown” were either solicitations from the Republican Party or pollsters and the occasional solicitation.
I don’t answer any calls from “Unknown” anymore.
Also, I don’t think cell phone numbers are even available to pollsters but I may be wrong about that. I live in WI but my cell phone # has a CA area code, long story, and if I was polled via my cell phone it would be useless info.
I moved back to the States after 14 years in Japan in late 2004 and put my number on the do not call list immediately. I did it again when I moved to Alaska (and I understand about your cell phone because my cell phone still has a Virginia number). I answer unknowns because we get calls from Japan and they show up as unknown. But in that time I have never received a call from a poll. That’s why I wondered if they have to abide by the no call list.