You will not notice a difference in sound quality between our phone and any other high quality cordless phone. Some of our phones are digital, providing voice quality similar to a corded office phone. When approaching fringe areas, you may experience static as with any cordless phone. Many of our phones include a commercial grade scrambler. Some systems, such as the EnGenius, are digital.
Digital transmission is inherently safe against eavesdropping.
Of call security is a concern, please consult us so we may recommend an appropriate system. You list a maximum range. Range can vary greatly from one application to another. A phone designed for a range of up to 50km in open space may deliver only 10km in a mountainous environment. If you have line of sight conditions and your antenna is set up properly, you can expect close to the maximum range.