Called my private, unlisted, on the do not call registry, land line.  Don't give that line number to anyone except direct family.  

Did not leave a message.

My caller id shows one of these, too.  They called while I was out.  Technically these "non-profit" organizations are a legal exception to the Do Not Call list.  Because of this I just say no instead of messing around with them like I do the outright illegal telemarketers.  I never contribute to them, and I do not recommend contributing to them because:
1. Caller ID signatures cannot be authenticated, therefore one risks giving information to possible scammers with forged signatures.
2. "Non-profit" could be a lot of "expenses" (salaries, telemarketer fees, etc.) with very little going to purported beneficiaries.
3. There is no message left promoting the purported cause.  That tells me that they don't want my contribution if it hasn't generated a fat commission.

I too continue to receive these calls, no message.  I Googled this number and it is registered to Brie Wetmore, 1407 N 10th St., Boise, ID 83702. I can find no further information on that address or name, other than a listing showing the names of her mother and father???

They say they are Idaho fraternal order of police

This is an agency that solicits donations that supposedly go to the Idaho State Police, Oregon State Police or the Florida State Police, etc.  I do not know if the money ever gets there; I believe it to be a scam.