On 1/16/24 02:45, D. Hugh Redelmeier via talk wrote:

They try to hide the fact that their "home phone" service is over
VOIP.  For one thing, I think that they have dedicated bandwidth so
saturating your internet service won't break your phone service.

Compared to the bandwidth customers have, VoIP doesn't even amount to trivial. For example, I get 1 Gb down and 50 Mb up from Rogers. A "toll quality" call requires 64 Kb in standard TDM systems (1 DS0). With VoIP, the CODEC can require less bandwidth. G.729a requires only 8 Kb/s, though I doubt they're using that much compression. Also, voice calls can be given priority over regular data.

By comparison with my 50 Mb/s upstream, the old TDM phone system had 24 DS0s in a DS1 (T1) and 28 DS1s in a DS3 (T3) for about 45 Mb. That's 672 phone calls!

With cell phones, the trend is the other way, with better than toll quality CODECs, often called HD voice. VoIP phones can also use the better CODECs.