To find out who decorated a particular room, try to call directly to the service provider. However, remember that by law this information is confidential, so these requests officially produce only the police and some law enforcement organizations of higher orders, for example, FSO, FSB, SVR and others. However, if you have no special relations with people from these bodies or you don't have a really good reason to issue you such information, you are unlikely something will happen.
Try to contact the companies of cellular operators directly. Although they are not allowed to divulge this information, they can go to you on concessions under certain circumstances. Maybe you find that friend of your friend works in that company and can help you. Don't try to understand how they will do it. The important thing is that you will receive the necessary information. Be prepared for the fact that the employee may request a considerable fee for this service.
Another way is the use of clever moves in the work with the Manager of the mobile operator. To do this, try to show some acting ability and to improvise. The situation is this: when you pay for the services when the operator sees personal details of who produces it. It is the information that you need to use if you really want to know who decorated the SIM card. So take a compassionate view and go to the Department of payment of cellular services. Don't forget to invent a "history". For example, tell the Manager that your best friend on a business trip, and he urgently needs to fill the balance of the mobile phone, so he asked you for a favor. Make sure that the operator has agreed to help you. If you will feel confident and follow your legend, the Manager will give you personal details of the subscriber. If you try and come up with a few reasons you may be able to get more information. If the Manager refused, just refer to another paragraph and continue the same process.