1. A method performed by a mobile terminal, comprising: initiating, by an application client on a mobile terminal, a call to a network application function; receiving, by the application client and from the network application function, a denial/validation request; generating, by the application client, an authentication request that includes non-standard Global Bootstrapping Architecture (GBA) syntax; converting, by a middleware function, the authentication request from the non-standard GBA syntax into a GBA authentication request that includes standard GBA syntax for a Universal Integrated Circuit Card (UICC); directing, by the middleware function, the GBA authentication request, in the standard GBA syntax, to the UICC; receiving, by the application client, GBA authentication information from the UICC that is responsive to the GBA authentication request; and sending, by the application client and to the network application function, validation data based on the GBA authentication information.