The main chip is a Spreadtrum SC6531, it’s a single chip based baseband transceiver aimed squarely at the low-end feature phone market. Based around an ARM926EJ-S processor — an entry point ARM, although one still capable of running a full operating system like Linux or Symbian. It’s actually overpowered for this phone, the chip provides support for a 2MP camera. You can pick up the SC6531 on AliExpress for around $3.00 a piece in small lots.
The other silicon present on the phone is the HunterSun HS8292U. It’s an RF chip for quad-band 2G GSM/GPRS cellular handsets at 850, 900, 1800, and 1900MHz. You can pick it up on AliExpress for under $2 a piece.
They want to ban the phones. Somebody made a sensible comment: Why not just jam the signal in prisons? Maybe that could have negative consequences on legitimate users but I'm sure there's a way to manage that too.