Abstract: A method, computer program, and computer readable medium are disclosed for maintaining communication between first and second mobile units communicating via first and second communications networks, respectively. The first and second units include, respectively, first and second protocol stacks and first and second session layers, which interface between the first and second protocol stacks and first and second software components acting within the first and second units, respectively. The first unit includes first communications hardware with associated drive routines for different communications networks. When the first unit switches from a first to a third communications network, the first session layer maintains communication by selecting the first communications hardware and drive routine required for the third communications network.

Abstract: The present invention relates to a method, computer program products, and a computer readable medium, for maintaining communication between a first mobile unit (1) and a second unit (2), where said first unit (1) communicates via a first communications network (A1) and the second unit (2) communicates via a second communications network (A2). The first unit (1) includes a first protocol stack (12) and the second unit (2) includes a second protocol stack (22). The first unit (1) includes a first session layer (11) which is adapted to function as an interface between the first protocol stack (12) and first software components (15) acting within the first unit (1). Similarly, the second unit (2) includes a second session layer (21) which is adapted to function as an interface between the second protocol stack (22) and second software components (25) acting within the second unit (2).

Abstract: The invention relates to a data network-based system (1′) which is adapted for data communication and which includes a number of users (2) belong-ing to a first category and a number of users (3) belonging to a second category. A first user (2) belonging to the first category is adapted to use a chosen security protocol (20, 21) to establish a secure session with a second user (3) belonging to said second category, and subsequent to positive authentication allow data com-munication to pass through a firewall (6). A means (8) pre-coupled to the firewall (6) is adapted to establish the identity of the first user through the medium of a handshake procedure (21) belonging to the security protocol (20), and to allow messages to be forwarded from the first user to the second user belonging to said secure session in response to accepted authentication.