Hi and welcome! I hate to be the one to burst your bubble, but tortoises are not dogs. They may end up coming to you, but it's not so much because you called as it is because your the bringer of food. As for housebreaking them, well that is even more of a wild dream. Now you can get them more use to going to the bathroom when you soak them, or even perhaps when you take them out of their normal enclosure, but they really are never potty trained. Sorry. Tell us more about your Russian though.
When you properly spoil them they will come running when they see you.. but no so much because you call them. If you don't have food you will promptly be given the stink eye.
I have trained Humphrey to come out of his hide when he is in his inside enclosure. I thump on the side of the enclosure and he looks out and then finally will walk out. The reward is that he either gets to go outside, get soaked, or gets to eat. So, I thump and he comes out. Yes, it does involve food most of the time, haha.
Yes, tortoises pretty much use their humans for food and to pay the electricity bill. Since they are wild creatures, really, we just get to watch and admire them.