A mobile telephone terminal provides a user with a selectable option to transfer a telephone call to an instant messaging session and to transfer an instant messaging session to a telephone call. A presence attribute indicator for a first party is displayed, in a mobile telephone application, with an entry associated with the telephone number of the first party. A user, while displaying an entry for a party in a mobile telephone application, has a selectable option for initiating instant messaging with the party. The mobile telephone provides a customised menu of selectable options for initiating communication. The menu is dependent upon received presence attribute information. A calendar application can store the content of an instant messaging dialogue in an appointment record. When an application accesses a stored telephone number of a party the stored instant messaging address of that party is automatically accessed or accessible and when the application accesses a stored instant messaging address of a party, the stored telephone number of that party is automatically accessed or accessible.