| 摘要 |
The present invention relates to a method and apparatus for establishing a connection, wherein a response to a call setup request of a first type of connection is checked by a signaling control unit and a signaling of a second type of connection received from the other party of the connection is monitored. A third type of connection is set up if the result of the checking step indicates that the setup was not successful. The second type of connection may then be set up when a signal indicating a support of the second type of connection has been detected in the monitoring operation within a predetermined time period. Since a preliminary fallback to the third connection is performed irrespective of the monitoring operation, a more common fallback case can be freed from a monitoring delay. (Fig. 3). Preferably, the monitoring step may be performed in response to the result of the checking step. Thus, the monitoring means is connected on line by the connection control means in response to the checking result of said checking means. Thereby, an unnecessary reservation of the monitoring function (e.g. IWF resource) can be prevented, since the monitoring can be restricted to those cases where the setup of the first connection was not successful. In this case, the response may be received as an outband signaling.
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