The mystery has been solved! I was home when the call came in tonight from this number. The person identified himself as Bryan from Pima County Fraternal Order of Police. I hung up on him so didn't stick around to hear his "speel." Presumably it was for a donation. I question the name of the organization because in the county the law enforcement agency is the Sheriff's Department and in the city it's the Police Department.
The solicitor did direct me to a website although when I asked if I could register my donation on the site rather than giving my card over the phone which I will never do! The solicitor hung up if this legit it needs to have a secure site to make credit card donations.