Techniques for performing messaging between mobile stations (MSs) and UMA network controllers (UNCs) in an unlicensed mobile access network (UMAN). URR (UMA radio resource) messages are exchanged between an MS and one or more UNCs to perform various operations associated with UMAN. The MS may access the UMAN via a wireless access point (AP) that is communicatively coupled to the UNC via an IP network. The URR messages are sent between MSs and UNCs using an Up interface comprising a set of layered protocols over an underlying IP transport.