I answered this call, then I hung up after 2 seconds, as is my practice when there is no name in the caller ID slot, and I don't recognize the number. This saves space on my digital answering machine. No risk, quick and clean.
The call is from Medco, and it's completely legit. If they ask for your address, they're trying to confirm that's where you want your prescription shipped.
BTW, the "Call Type" on this form needs an "Other" option.