This post is an example of the fine intellectual abilities of those with computers and internet access. This phone number actually is Geicko, although not only for billing/collections. So, if you got a call from this number, and you don't have Geiko, it may be that they misdialed, or have old information for one of their customers. You would possibly also get a call from this number if you were involved in an accident with someone who has Geiko.
Just had the same sort of Geico Insurance call. I went to their main website: http://www.geico.com/about/contactus/ and called them to see if the Tucson, AZ number was authentic. It is, they have a claims office based there and so the call is legitimate - they are researching for claims.