3GPP Layer 3 encode/decode functions are generated when the -3gl3 switch is specified on the command line. For each ASN.1 production defined in the ASN.1 source file, a C 3GPP Layer 3 encode function is generated. This function will convert a populated C variable of the given type into a 3GPP layer 3 encoded message.

C++ is not directly supported for 3GPP Layer 3; however, it is possible to call the generated C functions from a C++ program.