Interface between NodeB and RNC is called Iub, which consists of ATM stack (as transport protocol), and top of that there’s NBAP application protocol. IP is coming as option to replace ATM. Both AAL2 and AAL5 are used. Interface RNC and MGW is called Iu. ATM is also used here, but some vendors support IP already now. Voice circuits run AAL2. RANAP application protocol does here mainly the same job as BSSAP in GSM.