Mine didn't talk until 16 months. No mama, dada, hi or anything else. He was too busy walking, running, building, dragging things around, and so on. We knew that he could hear us so if that's not a concern for you, I wouldn't worry about it. He's doing other things and growing/developing in other ways.
At 16 months, he was still grunting and pointing, and I finally said "Whatever you want in that cabinet you're pointing to, you may have - just say the word so I know what you want." Clear as a bell, out came the word "COOKIE!" After that, he never stopped talking!
Try not to anticipate his every need, but don't turn nit into a battle either. He's kind of in charge of this! If he's hitting all his other milestones, and saying a few words, I'm sure he's on track. Don't look at the other kids - they are pushing water tables or other oversized objects around - maybe your kid is going to be like mine, who loved building and creating so much that he's not a civil engineer!