FIG. 1 is a block diagram of a first example of a communication system 100 that supports secure SMS messaging over NAS according to some embodiments. The communication system 100 provides support for both mobile and fixed access. As used herein, the term “mobile access” refers to accessing a communication system (e.g., the communication system 100) over an air interface. Mobile access can therefore be referred to as wireless access, mobile communication, wireless communication, or other similar terms. The term “fixed access” refers to accessing to a communication system using a device that is physically connected to the communication system, e.g., accessing a communication system such as the communication system 100 via wires, optical fibers, and the like. Fixed access can therefore be referred to as wireline access, wired communication, or other similar terms. The communication system 100 supports hybrid access that allows devices to concurrently access the communication system 100 using mobile access and fixed access.