Dial-up port on laptop and FXO


Can the dial-up port available on (old) laptops be considered as a true FXO port (cf for instance 3cx.com/PBX/FXS-FXO.html)?
If yes, (how) can Asterisk manage this port the same way than dedicated FXO ports on external devices, for routing from SIP to PSTN.
My plan is to install Asterisk on one such laptop , so that all calls from registered SIP users be routed to PSTN via the dial-up port connected to one of FXS ports of my ADSL box (which will route back to VoIP , but with private parameters/protocol not available).
Is this idea completely crazy?
Thank you for any suggestion
Best regards

As far as I know the driver support for general voice modems has been withdrawn, even if Linux did support the specific ones on the laptop. In any case, software solutions to the problem of echo cancellation tend to be a long way behind hardware ones.

I’m assuming that there is direct software access to the codecs on the port, and to the loop state information and that the programming model for accessing these has been made public. A self contained, hardware implementation, of a pure modem, would not be usable at all, but cheaper WinModems don’t actually have any modem hardware.

Thank you for your reply.
I’m just ignorant on telephony, so be indulgent with me, but it was possible at former time to use a PC/laptop as a phone, using a SW dialer, so I expect the problem of echo cancellation be solved to some extent.

But I understand that even if formally, my idea should be feasible, as nothing is ready in Asterisk for that, I should better forget it. Too bad, no rebirth for my old laptop!
Best regards

If it had voice “modem” capabilities, you would have been using it directly on an analogue, line, so there would be relatively low round trip delay, and echo suppression would not be needed. Once you involve VoIP, the delays are such that echo can be very distracting.