A contactless transaction adaptor for use with a mobile communicator, including a thin SIM card signal interceptor portion arranged for insertion intermediate an existing SIM card, having SIM card-based contacts, and communicator based SIM card contacts located in a SIM card recess formed in the communicator, the interceptor portion having contacts for communication with the communicator-based SIM card contacts and contacts for communication with the SIM card-based contacts, a contactless communication circuit bearing portion arranged for insertion in the communicator, a contactless antenna and a contactless communication circuit both mounted onto the circuit bearing portion, a flexible connector portion interconnecting the interceptor portion and the circuit bearing portion, an electrical path extending along the connector portion between the contacts of the interceptor portion and the contactless communication circuit, and an electrical path extending along the circuit bearing portion between the antenna and the contactless communication circuit.