The invention relates to a periodic location region updating method of a dual card dual standby
mobile phone with a single
GSM communication module. An antenna in the
mobile phone is connected with a
radio frequency circuit which is connected with a
baseband processor which is also connected with a memorizer, other control circuits and an analog switch; two SIM cards are serially communicated on the analog switch. The method comprises (1) whether the two SIM cards belong to the same operator is judged; (2) if so, an SIM card is selected to obtain a
cell parameter T3212 from a BCCH and the other SIM card obtains a
cell parameter T3212 from the first SIM card; (3) if not, whether the periodic location updating parameters are identical is judged, if so, the step (2) is turned to, and if not, the periodic updating of the SIM card is carried out independently; (4) a
timer is started by the SIM1 and the SIM2; (5) the location updating is independently started by the two SIM cards when the
timer runs to overflow. When the periodic location region updating is achieved for the dual card dual standby mobile pone by the single
GSM communication module, the application is convenient and the application range is wide.