At positive balance of the SIM card lock easily. If you went negative, to the mobile phone you need to make a certain amount of money, just enough to "break even". This is necessary in order that the operator will not collect money from you through the courts. Believe me, the amount you will have to pay then will be much greater.
If the balance on the phone all right, lock SIM card, contact the company representative via call-center or contact the nearest brand cellular operator. To "freeze" the old number, you can also on the Internet, logging on to the official website of your service provider.
If you were using a SIM card of MTS, for blocking numbers you can dial from cell 0890 or 766-0166 with the city. Your request will listen and come towards you. You can also leave a message on the website
Your mobile operator Beeline? To connect with a specialist call center 0611 dial from your mobile phone or 974-8888 with "home". To block your own number through the website of the company
To lock the SIM card provided by mobile operator MegaFon, you can use one of three phone numbers: 050, 555 and 507-7777. "Freeze" your room allows and official representative of the company on the Internet. Go to and select the service "Service-Guide".
Service locking the SIM card may be applicable. Specify the cost in advance. This can be done on the official websites of the companies online or by asking the operator, "your call center.