Info about Z80 machine

"The state of the art" does not mean using crap echo cancellers and crap codecs. Do that and, yes, you will get crap sound. But use POTS over bad copper, with an el-cheapo phone, and you will get bad sound out of it too. I have to agree with you that the best VoI (and cellular) have to offer is worse than the best POTS has to offer. But, in each case, that best is very rarely attained, and in any case is so good that most people can't tell the difference between them; on decent-quality (not the top of the line but not the made-in-Taiwan el-cheapo crap either) gear, I find VoI will usually lose to POTS on short-haul calls and beat it on the long haul (I'm not really competent to comment on cellular). I have personal experience with this; one of my employers does, among other things, VoI, and I have been the principal tech behind their offerings for almost as long as they've offered them. And, now, my home phone is VoI on their system, in a city two hours' drive away from them (ping says only about 24ms RTT, but it is still over long-haul links). The codec they use is not quite the null codec, but close - it uses u-law range compression, but nothing more than that. It eats 64Kbps of network per direction, but in practice, for their target market, that is not an issue. (They don't go after the mass-market individual end user, more small-to-medium businesses.) Your "real world" is very different from mine. Network delay large enough to be human-perceptible on our system is notably rare, and the sound is usually quite good. But, as I mentioned in a previous post, we also generally don't sell low-end phones. Yes. /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML mouse at rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B