A method and apparatus for operating a trust establishment system during at least part of a service-provision telephone call originally made from a calling party to a called party. An identifying code is received after the telephone call has been established. A stored token is retrieved on the basis of the identifying code. The stored token is transmitted from the trust establishment system to the calling party during the telephone call in order to establish the calling party's trust of a service provision system on behalf of the service provision system. The telephone call is passed from the trust establishment system to the service provision system for further processing, after the stored token has been transmitted to the calling party. The identifying code is preferably uniquely associated with the calling party and may have been transmitted to the calling party prior to the telephone call. The stored token may have been recorded or selected by the calling party prior to the telephone call, hence the calling party may establish trust with the called party by recognising the stored token.