Gregory's Server@sabi My first modem had several speeds. 300/300 full duplex, 1200/75 full duplex and 600/600 half duplex.. Based on a TCM3105 from TI. You couldn’t buy modems so a American friend bought me the chip and I built a modem myself. Taped out a circuit board and sold a few hundred modems over the next few years.
@burne you’re the winner of this thread so far, no one else has mentioned building their own modem!