I think they are trying to contact you. I have had something very similar as my grandfather passed away last year in November, and the funny thing is is that I never knew or met him since he is in another country. Before I knew he passed away, I had a dream about seeing a thin, frail looking old man with a smile. There was a bright, golden light behind him. He, however, didn't say anything; he just gave me an assuring smile. When my mom came back from visiting, she brought home a small wallet picture of my grandfather...who was the man in my dream. It makes sense that he didn't speak for I don't know any Vietnamese.
Without a doubt they are trying to contact you. Phones in particular are a symbol of communication, and dreams are places where other beings can contact you very easily. This includes the deceased commonly among them.