Abstract: A computer-implemented method is provided, including sending, to a plurality of mobile communication devices, respective messages that include respective message contents that differ from one another and respective human-readable instructions to dial a telephone number common to the messages. A telephone call placed to the telephone number is received from one of the mobile communication devices. One of the messages is identified as most recently sent to the one of the mobile communication devices. A call destination is selected responsively to the most recently sent one of the messages, and the telephone call is routed to the selected call destination. Other embodiments are also described.