Abstract: A push-to-talk communication device including an operating answer mode indicates that operating answer mode to a Session Initiation Protocol/Internet Protocol based push-to-talk network server. The method includes employing as the operating answer mode of the push-to-talk communication device one of an automatic-answer mode, an always-automatic-answer mode and a manual-answer mode. A Session Initiation Protocol/Internet Protocol core network is employed including a Session Initiation Protocol/Internet Protocol push-to-talk network server. The operating answer mode is indicated in a Session Initiation Protocol message from the push-to-talk communication device to the Session Initiation Protocol/Internet Protocol push-to-talk network server over the Session Initiation Protocol/Internet Protocol core network.

Abstract: Apparatus, and an associated method, for facilitating call connection with a selected service center from a mobile node. A mobile node is provided with short dialing codes used in a network with which the mobile node is registered by SMS messages sent thereto, such as pursuant to registration procedures. Values of the short dialing codes downloaded to the mobile node are stored at a storage location, such as at a SIM card, indexed together with corresponding codes normally used by a user of the mobile nodes, such as the codes used in the home network of the mobile node. When a user places a call to a service center, the stored values are retrieved, and transposed, if needed, to ensure better that the call to the selected service center is successfully completed.

Abstract: A push-to-talk communication device including an operating answer mode indicates that operating answer mode to a Session Initiation Protocol/Internet Protocol based push-to-talk network server. The method includes employing as the operating answer mode of the push-to-talk communication device one of an automatic-answer mode, an always-automatic-answer mode and a manual-answer mode. A Session Initiation Protocol/Internet Protocol core network is employed including a Session Initiation Protocol/Internet Protocol push-to-talk network server. The operating answer mode is indicated in a Session Initiation Protocol message from the push-to-talk communication device to the Session Initiation Protocol/Internet Protocol push-to-talk network server over the Session Initiation Protocol/Internet Protocol core network.

Abstract: Apparatus, and an associated method, for facilitating selection of a network with which a roaming mobile node communicates to effectuate a packet data communication service. A database is maintained at the mobile node indicating radio access networks together with their communication capabilities. The database is dynamically maintained and updated, if needed. When the mobile node roams and packet communications are to be effectuated, the database is accessed to determine with which of available radio access networks through which the mobile node should communicate.