The MS8503H1 designed for the SMS phone applications with the caller ID function.  It built-in to  OTP base micro-controller for operation of the entire system with up to 16K bytes RAM. It supporting up to 1M bytes ROM  and several I/O interfaces designed for handshaking with the other peripheral devices and provide two serial  interfaces and LCD interface.
    ■ The MS85321 including the functionalities of 
        ■ FSK transceiver
        ■ a high performance CPE Alerting Tone (CAS) detection
        ■ DTMF generation
        ■ Ring detection
        ■ Low Voltage indication. 

    ■ 8-Bit micro-controller built in
    ■ Operating voltage range: 2.5~5.5V
    ■ 256K bytes internal ROM (Up to 753K bytes external ROM)
    ■ 4K bytes internal RAM (External: 8K bytes.)
    ■ Power Management
        ■ Standby mode
        ■ Stop mode
    ■ Only single crystal (32768Hz)
    ■ Programmable MCU clock rate
        ■ High-Speed: 
            ■ 4.194MHz, 2.097MHz, 1.049MHz, and 0.524MHz.
        ■ Low speed: 32768Hz.
    ■ Input port and I/O ports interface. (32 I/O + 8 Mutil-I/O)
        ■ Input port: 8 pins with interrupt option.
        ■ I/O port A~B: 16 pins I/O ports with non-open drain structure.
        ■ Open drain I/O port: 4 pins.
        ■ Heavy driving output port: 4 pins.
        ■ Multiple-function I/O ports: MPORT0~7.
    ■ Low voltage detector
    ■ Two 8-Bit general-purposed timers
    ■ A watchdog timer against deadlock.
    ■ UART controller
    ■ Universal synchronous serial Interface (SSI)
    ■ Priority-based interrupts.
    ■ LCD driver interface
    ■ Memory Interface:(Parallel Interface.)
    ■ Ring and line reversal detector
    ■ FSK Transceiver & Carrier detector
    ■ CAS (CPE Alert Signal)/TAS detector
    ■ DTMF (Dual Tone Multiple Frequency) generator
    ■ DTMF Decoder
    ■ Ringer/Music tone generator

    ■ Calling number delivery (CND) 
    ■ Calling name delivery (CNAM) features
    ■ Caller identification on call waiting (CIDCW) features
    ■ Corded or Cordless adjunct boxes phone set
    ■ Short Message Service system.
    ■ Corded or Cordless Feature phones
    ■ Other communication systems

    ■ 128 Pins QFP packaged.