The item is AEX410 Asterisk card add VPMADT032 echo cancellation module,which is recommended when handling large call volumes or a high number of channels that would otherwise stress the CPU and result in the potential for poor audio quality
AEX410 Asterisk card supports up to four FXO/FXS ports, plug and play. Using AEX410 analog card, open source Asterisk PBX and stand alone PC, users can create their SOHO telephony solution include all the sophisticated features of traditional PBX, and extend features such as voicemail in IP PBX.
The AEX410 card is bundled with 4 FXO or FXS modules.
The FXO module is in red and the FXS model is in green .
FXO port connects to PSTN line and the FXS port connects to the telephone.
You can get any combination of FXO & FXS modules with the same price,no any additional cost.
