All the telephony interfaces are modular and customizable, whether it’s FXS, FXO, ISDN BRI/PRI, or GSM/3G/4G. S100, S300, P560, P570 require the combination of the Expansion Board and Telephony Modules to add interfaces.

  • S20 has 2 onboard module slots
  • S50, S412, and P550 have 4 module slots
  • P560 allows 1 Expansion Board
  • S100 and P570 support 2 Expansion Boards
  • S300 supports 3 Expansion Boards
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