1. 3G/HSDPA modem, minimum download speed 3.6Mbit/s, USB or UART interface, either module or chip solution (QCA)
2. WiFi module, chip or Wifi SoC - QCA4004 based module, or QCA4004 chip. Any reliable and cheap WiFi is acceptable. AR9331 or QCA9556 solution is acceptable too.
3. 4GBytes (32Gbit) eMMC memory.
4. Cortex M4 compatibile MCU to manage (1) and (2) and to decode MP3 audio, MCU with integrated AUDIO codec is preferred.
5. Power supply IC for voltages required by 1, 2, 3, 4 - linear regulators are acceptable.