We've been have the same problem. I finally was able to talk with someone and got information. The 712 945 0164 is a direct dial number, so you can't call them back. The caller is from National Union Fire Insurance Co in Pittsburg, PA. In our case, they were authorized by Homecomings Financial, a mortgage company to call us. The direct dial number for Natl Union (or the 712-945-0164 no.) is 800-781-8280. They will put you on the Do Not Call List if you request it.
We have been getting these calls from this number for sometime now. When answered no one would say anything. Now it rings three times and hangs up. They even call late at night and on weekends and it has gotten old. If someone would say something I would give them a good hello! How do I get on the do not call list?