A method for processing communications in a telephony network, the method comprising: processing at least one SMS message in SMS processing equipment in the telephony network, wherein first and second telephony identifiers are associated with a first user equipment used by a first, multi-identity user, and wherein the first and second telephony identifiers are useable as different destination addresses in different SMS messages sent to the first user equipment; and performing identity management, in relation to the use of the first and second telephony identifiers during said processing of the at least one SMS message at the SMS processing equipment, wherein said performing said identity management comprises: accessing stored data indicative of an association between at least one characteristic derivable from the at least one SMS message and at least one of the first and second telephony identifiers, wherein said at least one characteristic is a third telephony identifier derived from a destination address of said at least one SMS message, wherein said third telephony identifier is an identifier associated with a second user equipment used by a second user, wherein the stored data includes communication data relating to the first user, the communication data including data indicative of one or more previous communications involving use of the second telephony identifier and the third telephony identifier; and selecting the second telephony identifier on the basis of the communication data included in the stored data, wherein said processing at least one SMS message comprises transmitting an outgoing SMS message to the second user equipment associated with the third telephony identifier, wherein said outgoing message includes an originating address comprising the selected second telephony identifier, and wherein the telephony network comprises a circuit-switched core, a packet-switched core and gateway equipment connecting the circuit-switched core and the packet-switched core, wherein the gateway equipment implements transport layer interworking for SMS messages transmitted between the packet-switched core and the circuit-switched core, and wherein the identity management is performed at the gateway equipment. processing at least one SMS message in SMS processing equipment in the telephony network, wherein first and second telephony identifiers are associated with a first user equipment used by a first, multi-identity user, and wherein the first and second telephony identifiers are useable as different destination addresses in different SMS messages sent to the first user equipment; and performing identity management, in relation to the use of the first and second telephony identifiers during said processing of the at least one SMS message at the SMS processing equipment, wherein said performing said identity management comprises: accessing stored data indicative of an association between at least one characteristic derivable from the at least one SMS message and at least one of the first and second telephony identifiers, wherein said at least one characteristic is a third telephony identifier derived from a destination address of said at least one SMS message, wherein said third telephony identifier is an identifier associated with a second user equipment used by a second user, wherein the stored data includes communication data relating to the first user, the communication data including data indicative of one or more previous communications involving use of the second telephony identifier and the third telephony identifier; and selecting the second telephony identifier on the basis of the communication data included in the stored data, accessing stored data indicative of an association between at least one characteristic derivable from the at least one SMS message and at least one of the first and second telephony identifiers, wherein said at least one characteristic is a third telephony identifier derived from a destination address of said at least one SMS message, wherein said third telephony identifier is an identifier associated with a second user equipment used by a second user, wherein the stored data includes communication data relating to the first user, the communication data including data indicative of one or more previous communications involving use of the second telephony identifier and the third telephony identifier; and selecting the second telephony identifier on the basis of the communication data included in the stored data, wherein said processing at least one SMS message comprises transmitting an outgoing SMS message to the second user equipment associated with the third telephony identifier, wherein said outgoing message includes an originating address comprising the selected second telephony identifier, and wherein the telephony network comprises a circuit-switched core, a packet-switched core and gateway equipment connecting the circuit-switched core and the packet-switched core, wherein the gateway equipment implements transport layer interworking for SMS messages transmitted between the packet-switched core and the circuit-switched core, and wherein the identity management is performed at the gateway equipment.