Patent ID: 7693273

Claim:
In a communications network, wherein a source network unit conducts a new transaction for a function of that network by: (a) selecting a member of a respective function-associated pool of transaction-processing units, each having a service status of in-service (IS) and having a first network address for receipt of initial transaction signalling messages and a second network address for receipt of subsequent transaction signalling messages; (b) sending an initial transaction signalling message to that first network address of the selected member, and then sending subsequent signalling messages of that transaction to the second network address of the selected member; a method of changing the service status of a particular transaction-processing unit of the pool to out-of-service (OOS), the method comprising: (c) changing the service status of the first network address of the particular member from IS to OOS; (d) continuing to process subsequent signalling messages received at the second network address of the particular transaction-processing unit in respect of transactions currently being processed by that particular transaction-processing unit; and (e) changing the service status of that particular transaction-processing unit from IS to OOS upon detecting actual or effectual completion of all such transactions currently being processed by that particular transaction-processing unit.