| 摘要 |
<p>In order to upgrade a one-way message transmission system (10, 14, BS1 to BS3) to an answer-back system at minimum additional cost and inconvenience, an answer-back apparatus (20, 22, 24, 26) is provided which is coupled to a paging network controller (10) of the one-way message transmission system. The answer-back apparatus comprises a receiver (22) for monitoring messages transmitted to secondary stations (18) on a down-link, another receiver (20) for receiving responses from the secondary stations on an up-link and an answer-back network controller (26) for matching the responses to the messages and for issuing acknowledgements to be sent by the one-way system and for relaying the responses to be intended recipients. The answer-back network controller (26) labels messages to be sent on the down-link, the labels being used in matching the responses to the messages.</p> |
