Looking at the website you provided there is a long review that mentions something about having to change the wiring to get the phone calls to work. Look to that post, hopefully you can figure out what he is talking about.
There was a scary amount of google translate 'reviews' on the product. One even praising the customer supports English ability with pretty bad English.
We've had a few posts on these types of radios and I don't think we have ever been able to solve their problems. Like many products of this type, there are dozens of similar products created in either the same factory, or using the same components and then sold under different names. quality and functionality are all over the place, making it almost impossible for us to be much help. The jeep is being the best jeep it can be and this is not a jeep problem.
That being said, I'm willing to try as best I can. Many of us are not on here everyday, so if you don't figure it out bump the post after a couple days. The forums is active enough that a post can get buried really fast.
Also, please return and let us know if you figure it out, the next person that has this problem will thank you.