Sends a USSD command string to the network initiating a USSD session. When the request is handled by the network, the method returns the response or an appropriate error. The network may be awaiting further response from the ME after returning from this method and no new command can be initiated until this one is cancelled or ended. The command to start the USSD session with. The network response to the command which started the USSD session. Respond to a USSD request that is either initiated by the mobile network, or that is awaiting further input after Initiate() was called. The response to network-initiated USSD command, or a response to a request for further input. Cancel an ongoing USSD session, either mobile or network initiated. Indicates the state of any ongoing USSD session. Values may be one of the following: "idle" (no active session), "active" (a session is active and the mobile is waiting for a response), "user-response" (the network is waiting for the client's response, which must be sent using Respond()). Contains any network-initiated request to which no USSD response is required. When no USSD session is active, or when there is no network- initiated request, this property will be a zero-length string. Contains any pending network-initiated request for a response. Client should call Respond() with the appropriate response to this request. When no USSD session is active, or when there is no pending network-initiated request, this property will be a zero-length string.