Reply 20 of 21, by davidrg
Dan9550 wrote on 2024-12-10, 02:57:Had a look online an PBXes and wow does that make your head want to explode, a bit of specific knowledge required to wrap your h […]
Had a look online an PBXes and wow does that make your head want to explode, a bit of specific knowledge required to wrap your head around those. Plus if i dive into a PBX i don't really know if inside its working just like the ATA or not I'd be assuming otherwise.
I will try a little more playing around with the ATA and blind dialling since there is a dialling prefix (*99) that should tell the ATA you want modem pass through, it's worth a shot. Looking at my ATA configuration i also had G711.u set instead of G711.a which may make a difference.
Speaking of telephone networks this video dropped today and is relevant to this discussion to a degree even if the recommendation for messing around at home is a line simulator. Which is non-existent where i am.
Cathode Ray Dude - Here's All My Phone Stuff:
https://www.youtube.com/watch?v=dEEddujTlog
AFAIK your typical 90s PBX that supports regular analog phones should largely behave just like a regular telephone exchange. My Panasonic one makes the same noises (dial-tone, off-hook tone, etc) that the national telephone network did, supports both tone and pulse dialing, etc. The factory-reset default settings seem sane enough and probably no further configuration is really necessary, though it certainly isn't the easiest if it is needed - on my one it all has to be done through one of their proprietary phones, though newer models have computer software for doing it.
A lot of them are I guess sort of like an ATA in that they're not entirely analog devices just passing audio signals. Panasonic calls my one a "Super Digital Hybrid" PBX and its own proprietary phones are digital, not analog. So probably it is internally converting analog calls to/from digital and then just routing the digital signals around. But all real telephone exchanges have done exactly that for decades too, and if you wanted to pay for it you could in a lot of areas get digital (ISDN) telephones and modems. Every time you used a 56k modem to dial into the internet, somewhere your call was passing through a digital telephone exchange and being handed off to a digital ISDN modem which was answering your call (analog modems are incapable of answering 56k calls, only digital modems can do this).
So really the issue isn't so much "working just like an ATA", but rather "designed to support modems". I guess a lot of ATAs aren't really designed for high speed modems simply because people aren't using them to dial into their ISP for internet access. They're designed for lower-speed things like security alarms and fax machines. I'd think a 90s PBX is more likely to have been designed to not get in the way of high speed data calls simply because that's how a lot of small businesses would have connected to the internet back then.
