I'll be honest, this has happened to me. We tried to get Delta Airlines interested but everyone knows the Airline industry is in a decline, so that didn't go to well.
But, try to target mid sized companies or smaller companies. These are the companies that are smaller and are more willing to look into advertisement and community involvement. The larger companies are used to sponsorship hassles and stuff. But the smaller companies haven't experienced that yet.
As for phone calls, it's OK, but not good, I would prefer a personalized letter. Face to face can get a little hectic, like, all the traveling, and at times, maybe a little bit awkward.
So...
. Where are you guys located?