Hidden Voice Commands Could Attack Your Smartphone

[bruceb]

No, every dial tone line originates in a digital switch, usually a #5 ESS switch. The software within the switch detects what digits are sent to it, which tells it what phone number to connect to. If the call is local within the same exchange, it routes it directly. If it has to go to another exchange, then it goes over the SS7 channel to route it to the next exchange or if a long distance call, over to a Tandem Office, which then sends the call over to the end office to complete the long distance call. It is all explained at this link:

Just to clarify, on dial tone lines, the SS7 link is internal to the central office switching equipment. It never goes directly to the customer phone. And on Pay Phones, they use what is known as Ground Start Dialing, whereby the Tip connection (ground) is open, until it is momentarily grounded by the coin mechanism, which then allows it to get dial tone.

https://en.wikipedia.org/wiki/Signalling_System_No._7

 

[Mike64]

I think you are referring to key pulse or pulse dialing.

I was born in a unique time to use pulse dialing from a rotary phone and also DTMF dialing. Also used a record player on up to cassette. And I'm 36. The 80's were awesome!

Well, you, and everyone who's older than you… (I'm not old enough to be your father in anything but a don't-let-teen-pregnancy-happen-to-you After School Special sort of way, but I'm close.) DTMF dialing was actually "invented" in the mid-60s, it just didn't become at all widespread at the consumer level until sometime during the mid-late 70s, and it didn't become "the norm" until the 80s. (I don't actually know why not, unless it was just that for the vast majority of users, there was no functional advantage and leasing "Touch Tone" phones was more expensive than standard pulse-dial phones, before deregulation allowed people to connect their own, "privately-owned" phones to the lines at all.)

But unless you were paying close attention to pay phones in your childhood (not that that's really unlikely for an inherently tech-oriented person) you may not have ever even heard the "coin drop" sounds, which disappeared when the back end went digital (and the control channel was literally separated from the voice channel, as bruceb mentioned upthread.) When you inserted coins into the old analog-system payphones, you could hear a definite and distinct "control sound" being generated by the phone to indicate the denomination of the coin deposited. What I meant when I too-loosely used the term DTMF (to mean any multi-frequency sound) was that I don't think those were more complicated than single-frequency sounds, though offhand I don't recall ever having seen their frequencies published (and back in the day, High Times used to print a fair amount of phone-phreaking stuff, so the info was "out there" in a semi-mainstream way.) They definitely weren't any of "standard" keypad-generated DTMF tones. Nor were the "pulse" patterns, which were just timed interruptions of the phone line itself.

 

[John Connor]

But unless you were paying close attention to pay phones in your childhood (not that that's really unlikely for an inherently tech-oriented person) you may not have ever even heard the "coin drop" sounds

Yep! I do remember hearing the coin drop sounds.

Anyone remember the main character in War Games hacking that payphone by using a paper clip and grounding the receiver? I still wonder today if that was possible. It's probable since I'm sure what happened after you deposited the right amount of coins it grounded.

 

[Dwayne Weiser]

That would be...something. Something not that great. Although it doesn't sound that easy( it should make a specific noise, my phone would have to be nearby, not in my pocket I guess, and it should not interfere with other processes going on in it), maybe we should pay attention to things like our bank account and 'smell' any fishy activity when logging into your myciti account, for instance. I regularly check it at the bank when I have the chance (I try to do it once a month or every two other months), and get a statement of the activity every week. Your financials are not something to play with...