The object is to cater for the long-standing need for a failsafe device that consumes as little
data capacity as possible, said device being intended to effectively enable
authentication of a caller ID and associated
telephone number at the
receiver. Proceeding from the good approaches from the field of ISDN technology, the solution is provided by a
data channel, in the form of a parallel, strictly assigned
authentication network consisting of a multiplicity of interfaces that does not make available any additional data
payload whatsoever besides for the purpose of
authentication. Consistently restricting the data packets able to be received to a few bytes and the responses able to be issued to a few bits enables a high degree of redundancy and allows implementation in the form of a
system-relevant security component.