Abstract: A method and an apparatus for determining validity of a mobile subscriber identifier in a mobile communication terminal are provided. In the method, a temporary identifier assigned from a network is stored in a memory and a SIM card of the terminal. When a network authentication event occurs, the temporary identifier stored in the memory is compared with the temporary identifier stored in the SIM card. An identifier to be transmitted to the network is determined among an International Mobile Subscriber Identity (IMSI) and the temporary identifier stored in the SIM card depending on a result of the comparison.

Abstract: A method and an apparatus for determining validity of a mobile subscriber identifier in a mobile communication terminal are provided. In the method, a temporary identifier assigned from a network is stored in a memory and a SIM card of the terminal. When a network authentication event occurs, the temporary identifier stored in the memory is compared with the temporary identifier stored in the SIM card. An identifier to be transmitted to the network is determined among an International Mobile Subscriber Identity (IMSI) and the temporary identifier stored in the SIM card depending on a result of the comparison.

Abstract: A method and an apparatus for controlling power for transmission of a preamble for acquisition of a channel are provided. The method for controlling power for transmission of a preamble includes calculating an initial preamble transmission power using an initial power calculated using information broadcast through a forward common channel and a stored difference value, transmitting the preamble through a backward common channel with the initial preamble transmission power and replacing the stored difference by a difference obtained by subtracting the initial power from the initial preamble transmission power and storing the obtained difference instead of the stored difference, when an acknowledge to the preamble is received.