A method for processing a message in a wireless communication network, the method comprising: generating, at a first apparatus, a message comprising protocol discriminator information and one of security header type information and Evolved Packet System, EPS, bearer identity, wherein the protocol discriminator information indicates one of an evolved packet system, EPS, mobility management, EMM, message, an evolved session management, ESM, message and a protocol discriminator extension; and transmitting the message to a second apparatus, wherein when the protocol discriminator information indicates one of an evolved packet system, EPS, mobility management, EMM, or an evolved session management, ESM, message, the protocol discriminator information uses bits coded as 0010 to indicate an ESM message and uses bits coded as 0111 to indicate an EMM, message, wherein when the protocol discriminator information indicates an EMM message, the security header type information uses bits coded as 0000 to indicate that the message is not security protected, uses bits coded as 0001 to indicate an integrity protected message, uses bits coded as 0010 to indicate an integrity protected and ciphered message, and uses bits coded as 1100 to indicate a service request message, wherein when the protocol discriminator information indicates an ESM message, bits 5 to 8 of a first octet of the message indicate the EPS bearer identity, the bits 5 to 8 of the first octet of the message are coded as 0000 to indicate that no EPS bearer identity is assigned, and the bits 5 to 8 of the first octet of the message are coded as 0101 to 1111 to indicate an EPS bearer identity value, wherein when the protocol discriminator information indicates an EMM message, bits 1 to 4 of a first octet of the message contain the protocol discriminator information and the bits 5 to 8 of the first octet of the message contain the security header type information, and wherein when the protocol discriminator indicates a protocol discriminator extension, the bits 1 to 4 of the first octet of the message contain the protocol discriminator information and the bits 5 to 8 of the first octet of the message contain protocol discriminator extension information, wherein the first apparatus is a mobile station and the second apparatus is a Mobility Management Entity, MME, or wherein the first apparatus is a Mobility Management Entity, MME, and the second apparatus is a mobile station. generating, at a first apparatus, a message comprising protocol discriminator information and one of security header type information and Evolved Packet System, EPS, bearer identity, wherein the protocol discriminator information indicates one of an evolved packet system, EPS, mobility management, EMM, message, an evolved session management, ESM, message and a protocol discriminator extension; and transmitting the message to a second apparatus, wherein when the protocol discriminator information indicates one of an evolved packet system, EPS, mobility management, EMM, or an evolved session management, ESM, message, the protocol discriminator information uses bits coded as 0010 to indicate an ESM message and uses bits coded as 0111 to indicate an EMM, message, wherein when the protocol discriminator information indicates an EMM message, the security header type information uses bits coded as 0000 to indicate that the message is not security protected, uses bits coded as 0001 to indicate an integrity protected message, uses bits coded as 0010 to indicate an integrity protected and ciphered message, and uses bits coded as 1100 to indicate a service request message, wherein when the protocol discriminator information indicates an ESM message, bits 5 to 8 of a first octet of the message indicate the EPS bearer identity, the bits 5 to 8 of the first octet of the message are coded as 0000 to indicate that no EPS bearer identity is assigned, and the bits 5 to 8 of the first octet of the message are coded as 0101 to 1111 to indicate an EPS bearer identity value, wherein when the protocol discriminator information indicates an EMM message, bits 1 to 4 of a first octet of the message contain the protocol discriminator information and the bits 5 to 8 of the first octet of the message contain the security header type information, and wherein when the protocol discriminator indicates a protocol discriminator extension, the bits 1 to 4 of the first octet of the message contain the protocol discriminator information and the bits 5 to 8 of the first octet of the message contain protocol discriminator extension information, wherein the first apparatus is a mobile station and the second apparatus is a Mobility Management Entity, MME, or wherein the first apparatus is a Mobility Management Entity, MME, and the second apparatus is a mobile station.