A method for decentralized processing of signaling messages in a multi-application processing environment, the method comprising: (a) receiving a signaling message at a communication module associated with a screening module; (b) determining at the screening module, from a screening policy, at least two applications to perform message processing on the signaling message; the method characterized in that: (c) modifying at the screening module, the signaling message to include application routing information to allow the at least two applications to complete signaling message routing, wherein the application routing information comprises a list of network addresses useable by the at least two applications to route the signalling message between the at least two applications and to a destination, and a dirty bit field associated with each of the at least two applications, each dirty bit field configured to be modified when its corresponding application processes the signaling message; (d) forwarding by the screening module the modified signaling message to an application of the at least two applications, and at said application: (e) modifying the dirty bit field at the application to indicate that processing by the application is complete; and (f) routing by the application the signaling message using the application routing information to either a further application of the at least two applications which has not modified its dirty bit field, or, in case processing by all applications is complete, back to the communication module which then forwards the signalling message to the destination. (a) receiving a signaling message at a communication module associated with a screening module; (b) determining at the screening module, from a screening policy, at least two applications to perform message processing on the signaling message; (c) modifying at the screening module, the signaling message to include application routing information to allow the at least two applications to complete signaling message routing, wherein the application routing information comprises a list of network addresses useable by the at least two applications to route the signalling message between the at least two applications and to a destination, and a dirty bit field associated with each of the at least two applications, each dirty bit field configured to be modified when its corresponding application processes the signaling message; (d) forwarding by the screening module the modified signaling message to an application of the at least two applications, and at said application: (e) modifying the dirty bit field at the application to indicate that processing by the application is complete; and (f) routing by the application the signaling message using the application routing information to either a further application of the at least two applications which has not modified its dirty bit field, or, in case processing by all applications is complete, back to the communication module which then forwards the signalling message to the destination. (e) modifying the dirty bit field at the application to indicate that processing by the application is complete; and (f) routing by the application the signaling message using the application routing information to either a further application of the at least two applications which has not modified its dirty bit field, or, in case processing by all applications is complete, back to the communication module which then forwards the signalling message to the destination.