In a telecommunications system a data function and a date control function
are replicated in a plurality of databases (50, 51, 52, 53, 54). In order
to synchronize updating of the databases (50, 51, 52, 53, 54), one
database is identified as a primary database (50), at least one is
identified as a primary standby database (51), and the others identified
as secondary databases (52, 53, 54). Then, in normal operation, the data
control function of the primary database (50) is arranged to generate
signals for synchronized updating of the other databases. In the event of
a failure of the primary database, the or a standby primary database (51)
takes over the up-grading operating. Tee present invention is
particularly, but not exclusively, directed to a telecommunications system
for mobile telephones.
