A method for presenting tailored calling party data in a mobile client device in connection with a voice call, the method comprising: - initiating the voice call in a mobile client of a calling party, characterised in that the method further comprises: - sending a pre-call message from the calling mobile client to a library server, the pre-call message concerning identification information of a called mobile client whereto the calling mobile client is starting to establish a voice call; - the library server - informing the called mobile client of a forthcoming call from the calling mobile client; - checking from the called mobile client if it accepts to receive a tailored calling party data of the calling mobile client, and if allowed; - sending the tailored calling party data of the calling party to a mobile client of a called party; and thereafter - sending to the calling mobile client an OK message depicting that the calling client data of the calling mobile client is sent to the called mobile client and instructing the calling mobile client to send a voice call initiation message; - sending the voice call initiation message (56a, 56b, 39) from the calling mobile client to the called mobile client; - connecting (56a, 56b) the voice call from the mobile client of the calling party to the mobile client of the called party; and - presenting (57, 40) during alerting the incoming call a tailored pre-call calling party data that is at least a part of the tailored calling party data on a display of the mobile client of the called party. - initiating the voice call in a mobile client of a calling party, - sending a pre-call message from the calling mobile client to a library server, the pre-call message concerning identification information of a called mobile client whereto the calling mobile client is starting to establish a voice call; - the library server - informing the called mobile client of a forthcoming call from the calling mobile client; - checking from the called mobile client if it accepts to receive a tailored calling party data of the calling mobile client, and if allowed; - sending the tailored calling party data of the calling party to a mobile client of a called party; and thereafter - sending to the calling mobile client an OK message depicting that the calling client data of the calling mobile client is sent to the called mobile client and instructing the calling mobile client to send a voice call initiation message; - informing the called mobile client of a forthcoming call from the calling mobile client; - checking from the called mobile client if it accepts to receive a tailored calling party data of the calling mobile client, and if allowed; - sending the tailored calling party data of the calling party to a mobile client of a called party; and thereafter - sending to the calling mobile client an OK message depicting that - sending the voice call initiation message (56a, 56b, 39) from the calling mobile client to the called mobile client; - connecting (56a, 56b) the voice call from the mobile client of the calling party to the mobile client of the called party; and - presenting (57, 40) during alerting the incoming call a tailored pre-call calling party data that is at least a part of the tailored calling party data on a display of the mobile client of the called party.