I have had luck with a few, but as someone else suggested it depends on how easily influenced the person is.
Write their name and number on a sheet of paper. Place under your phone and visualize this person contacting you, and what you would like to say to them.
Write your intentions on a bay leaf (__ will contact me soon) and light it visualizing them doing so.
Of course if the person really does not wish to contact you, they will probably not be effected. I tested this once with a friend of mine. They said that "out of nowhere" they thought about me and wondered how I was doing, and called. I told them afterwards what I did. Though the only reason I needed them to contact me was I lost their number.