| 摘要 |
A telecommunications network architecture is known comprising a switching system for effecting basic call processing to set up, maintain and clear calls, and service-providing means (SPA) communicating with said switching system for providing services additional to said basic call processing. Due to the high availability requirements typically placed on telecommunications networks, the service providing means will generally need to be of a fault-tolerant design. A fault-tolerant architecture is provided that relies on the checkpointing to a reliable store (55) of state data for services currently being provided from first service logic (50) of the service-providing means; should the first service logic (50) fail, a second service logic (52) is brought into operation and provided with required state data on current services from the backup store (55). To reduce the amount of checkpointing of data by the first logic (50), state data is only checkpointeed when the correspponding call has reached a stable phase, the loss of a call during setup being much more acceptable than after it is been established.
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