The TetraFlex® Dynamic Subscriber Assignment is a new interesting feature, that together with the scalable and compact TetraFlex® system, provides a future oriented safe solution to secure communications at ”black spots” where currently established TETRA infrastructures, such as country- or region wide public safety networks have lack of coverage. The feature makes it possible for subscribers of any TETRA “home” network, automatically to be included in the TetraFlex® “guest” network within seconds. With a dynamic and automatic registration process no subscriber management is needed. While saving operational costs, users benefit of an instant and full end-to-end encrypted communication, with a full set of TETRA features available.