Specifications

Chapter 2 – SocketModem (MT5600SMI & MT5656SMI)
Multi-Tech Systems, Inc. Universal Socket Hardware Guide for Developers (S000342C) 46
Differences - Legacy Voice Modems and
Current Modems
Differences between the SFxxxD/SP and the MT5656SMI
Note: The SFxxxD/SP is the legacy voice modem with speakerphone I/O.
Pin 54 – “VC” This pin provided a reference voltage that is available from the data pump. This pin is not
supported on the MT5656SMI SocketModem.
Pin 55 – “~Voice” This function, when active, closes the relay to switch the handset from the telephone line to a
current source to power the handset where it could be used as a speaker and microphone
interface to the modem. This pin is not provided on the SocketModem
Pin 57 – “LCS” (Line Current Sense) When enabled, the LCS input indicates whether the associated handset
of off-hook (high) or on-hook (low). This pin is not available on the MT5656SMI SocketModem,
but the functionality is part of the Smart DAA.
Pin 58 – “Telout” (Telephone Handset Output). This pin is not supported on the SocketModem.
Pin 59 – “Telin” (Telephone Handset Input). This pin is not supported on the SocketModem.
Pin 60 – “Micm” (Microphone Modem Input). This pin is not supported on the SocketModem.
Pin 62 – “Micv” (Microphone Voice Input). This pin is supported on the MT5656SMI SocketModem in the same
way as the "SF" modem.