Patent ID: 7609675

Claim:
A system for recognizing a call switch-over to a CDMA 2000 1X system (1X system) when a call drop of a hybrid access terminal with respect to a CDMA 2000 1xEV-DO system (1xEV-DO system) occurs, the system comprising: the hybrid access terminal operated in a 1X mode in relation to a 1X system for receiving a voice signal transmission service or a low-rate data transmission service from the 1X system and in a 1xEV-DO mode in relation to the 1xEV-DO system for receiving a high-rate data transmission service from the 1xEV-DO system, the hybrid access terminal in traffic with the 1xEV-DO system being switched into the 1X mode to perform a call connection with the 1X system and to transmit/receive voice and/or data to/from the 1X system when voice signals or low-rate data are received from the 1X system; a 1X transceiver for transmitting/receiving voice signals and/or low-rate data to/from the hybrid access terminal; a 1X controller for controlling a transmission service of the 1X transceiver; a 1X mobile switching center for providing a communication access path of the 1X system for voice signals and/or low-rate data to/from the hybrid access terminal, storing information of the hybrid access terminal registered in the 1X mobile switching center in a home location register (HLR), and storing information of hybrid access terminals located in a region of the 1X mobile switching center; a 1xEV-DO access network transceiver subsystem for transmitting/receiving high-rate data to/from the hybrid access terminal; and a 1xEV-DO access network controller for controlling a high-rate data transmission service of the 1xEV-DO access network transceiver subsystem, detecting a call drop between the 1xEV-DO system and the hybrid access terminal in traffic with the 1xEV-DO system, and when the call drop is detected transmitting a message to the 1X mobile switching center to inquire whether or not voice signals or low-rate data are received in the hybrid access terminal, recognizing that the hybrid access terminal is switched into the 1X mode when a message confirming that voice signals or low-rate data are received in the hybrid access terminal is received from the 1X mobile switching center, and storing the recognition information so that a user knows the reason for the call drop.