using regular phone as voip device with regular modem?

Is it possible to use my regular (old) telephone as a speak/hear-device
(sort of headset) with softphone/voip-software through my old dial-up
modem? Something like the modem converts the analog audio signal from
the telephone to wave?

 

Very few modems are able to work this way even if you have the software to
do this. Best bet is a special usb phone or a phone adapter that connects
your phone to the internet without a computer. Digium modem cards and
asterisk is the reason the answer is not "no". This is way more than most
people want to do and adapters/usb phones can be found for less than $100
usd.

 

Maybe you could adapt an old handset from an analog phone and plug it into
the microphone and speaker jacks on a full-duplex sound card. That, with
the softphone software might work. I haven't seen any information that
indicates that VOIP is doable with a standard dial-up connection though.
That said, I would just get a cheap headset instead of trying to reinvent
the wheel, especially since the weak link will be the dial-up connection.

You could always download one of the free softphones and give it a try with
your dial-up line.

 

If it's a regular telephone then you need to use an ATA device. This
provides a 'dial tone' to a regular telephone. Also know as an FXS port.
They're generally around $90. Others can be had that will connect an old
phone to the USB port of a PC. These are around $50 but require the PC be
running to use the phone, whereas an ATA is stand-alone.

A 'old dial up modem' has little use for VoIP activities.

 

I will prefer use my old phone instead of a headset - the phone is made
for the purpose. I will try making it go into the sound jacks

 

I will prefer use my old phone instead of a headset - the phone is made

The headset about 600 ohms should work ok on the soundcard but the mic if
carbon element may need some matching.

This has some good ideas:

http://www.epanorama.net/circuits/teleinterface.html#interference