Called, rang once and hung up before I could answer.
A little searching around shows about the same results, with a few people saying that it's a robo-call from some company trying to sell pharmacy cards and at least two people saying they check for call backs so as to find numbers to sell.

Called and didn't leave msg.... Probably bill collector

They are calling my cell and hanging up

Called at 9:00 p.m. last night - no message. SCAM trying to take advantage of the upcoming deadline for Covered California enrollment. The scamming company is calling themselves "National Benefits Enrollment Department" to confuse and mislead people into thinking that they are the legitimate government agency
"National Center for Benefits Outreach and Enrollment" which helps elderly, low income people in need of assistance.
Please report this scamming company as often as possible. They are not only confusing the naive, they are preying on the elderly, ill and poor. This is criminal behavior!

Scam as stated above, received 2 calls so far even after speaking to the woman to cease immediately.
I am growing irritated.