Voice mail systems come in two basic designs, PC-based and proprietary.

PC-based systems
Most newer systems are PC-based, meaning they use a standard desktop PC as the core of the system. Manufacturers then add voice boards to peripheral slots in the back of the computer, and write software to run on OS/2, Windows or other high-end desktop operating systems. These systems are then integrated to work with phone systems.

The greatest advantage of PC-based systems is their low cost. Because these systems use widely available PC components, they benefit from the lower prices associated with mass production.

Proprietary systems
Most older systems are based on proprietary hardware. These systems are designed from scratch to store voice messages, and typically use operating systems developed specifically for messaging. Today, proprietary systems are strongest at the high end of the market, where concerns of stability and size outweigh the lower cost of PC hardware. There are also a few proprietary systems designed for the low end of the market. These are usually non-expandable systems designed for very small businesses.