Abstract: A method is disclosed for transmitting video images over a data communication network, in which method the video image is encoded at the sending end, transmitted, and decoded at the receiving end. The first frame is compressed and transmitted to the receiving end where it is stored in image memory. A copy of the first frame is retained at the transmitting end and divided into blocks. The next frame is also divided into blocks. The blocks of the first frame and the blocks of the next frame are compared to determine a block difference for each block. For each block, the difference between successive blocks is compressed and transmitted if the block difference for the block exceeds a predetermined threshold.

Abstract: A system and method for determining an urgency class of a disturbance occurring in a base station of a cellular communication system. A list of possible disturbances that can emerge during the functioning of the base station and the preliminary urgency classes determined for the disturbances concerned is maintained in a memory. In order to enable more accurate urgency classification, a preliminary urgency class is searched out from the memory corresponding to disturbances in question. An alarm urgency class is conditioned with the communications state of the base station by detaining a less urgent class than the preliminary urgency class when the communications state of the base station is peaceful (i.e., not busy). When the communication state of the base station is busy, a more urgent class than that of the preliminary urgency class is determined for the alarm.

Abstract: A method for enabling a customer, residing at a fixed address, to conduct business transactions with a business service provider using a teleterminal connected to the business service provider's central service center via a telecommunications network, and for verifying whether the customer has rights to conduct the business transactions. The central service center includes a contract database for storing contracts for business transactions that may be conducted by the customer, and an identification database for storing identification data representative of the customer's identity, and customer rights data comprising contract symbols representative of the customer's rights to conduct the business transactions.

Abstract: A method for placing a call from a first mobile station to a second mobile station using predetermined abbreviated dialing. An A-subscriber dials a short number at the first mobile station which is received by a mobile telephone exhange. The short number is compared to a group of short numbers each having an associated public telephone number corresponding to a unique second mobile station. If a match is found, the associated public telephone number is dialed and a coomunication path is established between the first and the second mobile stations. A billing record of this communication path is recorded at the mobile telephone exchange. Furthermore, the communication between the first and the second mobile stations may be marked as a transferred call to prevent further call transfers.

Abstract: A wireless PBX system having at least one predetermined coverage area, and having a predefined group of mobile communication devices associated with each predetermined coverage area is provided. Each of the mobile communication devices belonging to a predefined group includes a first telephone number by which the mobile communication device may be reached via a wireless network, and a second, short extension number, identifying the mobile communication device as belonging to a particular group. Mobile communication devices within one of the at least one predefined groups may reach other mobile communication devices within their group or within another group by dialing the second extension number of the desired recipient mobile communication device, and may reach other communication devices not associated with any group by dialing an appropriate telephone number.