A method of using a telecommunications network cashless transaction service is provided, in which a user accesses the service using a network access instrument, such as a mobile phone which produces a signal. The signal is forwarded to an interface device of the network, which extracts service and user identity data therefrom, and passes the data to a processing unit for the service of the network. The service processing unit processes the data, instructs the interface device to forward the access instrument signal to an input output device of the network, and instructs the input output device to request transaction details from the user. The details are sent to the input output device, which passes them to the service processing unit which processes the details and decides whether or not the transaction can proceed, causes output of a signal conveying acceptance or rejection of the transaction to the user, and, if the transaction can proceed, arranges for the transaction to be carried out. The telecommunications network may comprise a fixed network, the interface device may be a service switching point, the service processing unit may be a service control point, and the input output device may be an interactive/intelligent voice recognition unit.