To clarify the meaning - I'm talking about when your phone is locked to one network provider and you cannot use a SIM card from another provider without first 'unlocking' your phone. To do this you usually have to obtain (possibly for a fee) an unlock code from the original provider. I assume that the same system exists in Russia? And, in this case, how would I say "Is your phone locked [to a network]?" and "You need to unlock your phone"?
спасибо