Reference: RBD-1412
TTGO T-Call ESP32 Wireless Module GPRS Antenna SIM Card SIM800L Board
Chipset :ESPRESSIF-ESP32 240MHz Xtensa® single-/dual-core 32-bit LX6 microprocessor FLASH: QSPI flash 4MB / PSRAM 8MB SRAM:520 kB SRAM Button: Reset USB to TTL: CP2104 Modular interface: UART,SPI,SDIO,I2C,PWM,TV PWM,I2S,IRGPIO On-board clock:40MHz crystal oscillator Working voltage:2.7V-3.6V Working current: About 70mA