Abstract: A system and method monitors telephone networks and/or data communication networks, especially cellular mobile telephone networks (CeN), and provides good evidence of performance and quality of the services to be delivered by the network. At the same time, the system and method is easy to handle and includes components that require only small spaces and that are effective in use. According to the invention, a method and system (CeNA) includes one or more fixed and/or mobile units (FTU, MTU), herein designated as field units or test units, that enable quality observations and communication with a network operator or operation center (CU).