phone can work as long as the antenna is collectively connected

phone can work as long as the antenna is collectively connected.
Power management, including management portion of the input power, output power management section, the charge management section, the analog to digital conversion part, the DBB interface section, the user interface part. Phone board using a 720mAh lithium-ion battery. Charger switching power supply, the CC / CV mode. Voltage of 5.0V, current of 500mA. Output power management section to: TWL3014 internal include multi-channel LDO to meet the system power requirements, respectively, for the DBB, the SRAM, NOR FLASH, the IO, ABB analog circuits, the SIM card as well as real-time clock circuit. Off-chip voltage regulator modules: external DC / DC and LDO chip multimedia co-processor, camera modules, LCD modules required to meet the specific voltage, current needs. Normally, the phone system installed in the prison will be installed at a high position or a relatively hidden position so that it is not easy to be found.
The charging process is divided into three stages of the pre-charge, constant current, constant voltage charging lithium-ion battery management module. External 4-channel ADC: ADIN-4 for temperature detection, the other three-way set aside. Phone is switched on, the first downlink channel search signal, and to the search signal in accordance with the strength of the order of arrangement, to check whether there is a broadcast channel. When a broadcast channel, according to the frequency calibration channel and synchronization channel to adjust the internal frequency and timing synchronization with this broadcast channel. Then the mobile phone by comparing the SIM card of the machine recorded the MCC and MNC is consistent with the information sent on the Broadcast Control Channel. The mobile phone has been repeat the above process until you locate and lock the best part of this network broadcast channel. The complete system log function can record the working status of every phone .
Phone to the base station and then to report their own information and location: send the random access channel request, the base station to respond to access grant channel, dedicated control channel and then into separate two-way communication, the exchange of control data, and finally end the call. This completes the logon to the network. At this point, the phone has been able to calls and receive incoming communications. It should be noted, if the phone without a SIM card, the phone will still be completed to find and locked the procedures of the broadcast channel, but can not develop the radio to the registration and location update.