There is no way to persuade a child to do anything that child isn't ready to do. Remember that as your son (and daughter) grow, and you will save yourself a lot of gray hair!! :)
My niece didn't crawl until she was a year old. Then she was 14 months before she started pulling up to things. Finally, when she was nearly 16 months, she started walking. We haven't identified any other sort of problems ... she's talking and she's happy ... just didn't feel like walking, I guess!
With that said, we bought my nephew one of those toys he could hold on to as he walked behind it, pushing. I think it cost about $20. We bought it after he had started pulling up to things on his own, and he was walking in a matter of days afterward. However ... HE was only 9 months old. Kids just have different developmental clocks, and we have to respect them. My daughter didn't walk until she was 3 (but then, she has lots of developmental delays). But she walked ... imagine my surprise the day she walked into the room for the very first time, while I was working and not paying any attention!!
Your guy will walk. Enjoy this stage while you can. :)