I love it when someone puts the conference call on hold instead of mute. Then everyone gets to listen to their "Smooth Jazz" royalty-free hold music.
Oh gawd. It’s funny you should mention that.
Right after we lost the battle to have silent hold on our phone system, most people had FINALLY stopped using the various “free” conference call services when we kept pointing out the new expensive phone system had a conferencing bridge built in.
Guess what people started doing? Hold button instead of mute button. Or taking a call on their second line forgetting that hold now plays the crappy music the call center wanted...
Beat. Head. Here.
By the way, if you feed a digital conference bridge fed with old D4/AMI T1 circuits instead of ESF... the telecom geeks will know what that is...
And you put all 24 phone lines from that T1 into the same conference call. Or an even bigger, say any denomination of 24 up to the maximum capacity of your bridge... or linked bridges...
You see, non-ESF (SuperFrame vs Extended Superframe) uses “robbed bit” alarm signaling. One bit of the audio path is stolen every so often and ignored in the audio to send or receive remote alarms on the circuit.
So if you put all the exact same *sound* and a sound with a high amount of musical or other pitches with harmonica that ring on all of those channels...
You’ll set the second most significant bit across all of the channels for long enough to trigger a remote Yellow Alarm on that T1.
And... when you do that to hundreds of phone lines across multiple tens of T1 circuits at the same time...
You can crash the Cheyenne, WY MCI central office switch. Multiple times. In a single weekend.
Nobody could figure out why large chunks of a multi-hundred line conference call kept dropping simultaneously on that multi-bridge system until I put all of the lines on music hold during testing one Saturday during down-time testing to find the problem, and then thought “Hey, I think I know what’s happening here...”
To prove it, I manually dialed hundreds of lines back in and then injured only the operator line and whistled into the operator headset.
240 lines dropped instantly and then a pager message got me to call the on call engineer that weekend,
“You guy’s doing anything to those MCI circuits out of Cheyenne?”
“Just that span drop root cause testing they were asking for, why?”
“You crashed the MCI switch. They’re kinda ****ed at us.”
Ahh the bad old days.
Yes. I said MCI and pager. It was that long ago. Hahaha.