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Comment by dylz | Hacker News Reader

The kind of ATM I see at gas stations usually seem to involve a legacy ethernet cable of some sort (I've been told it's probably RJ12) and/or a small antenna magnet-mounted to the top of it. Not sure if they both serve the same communications purpose.

The few times I've used one they also take a ridiculous amount of time to connect/return anything, on the order of 30s-1m.

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This comment makes me feel old. The 2/3 sized cat5 jack is actually an RJ11 - what we used to call a 'phone jack'

Lol yeah "legacy ethernet cable" cracked me up, it's a phone jack :)

RJ12 is a thing: https://en.wikipedia.org/wiki/Registered_jack#RJ12

The jacks official name for the jack is Modular connector[1]. 6P6C for RJ14, 6P2C for RJ11 and 8P8C for RJ45 (what you described as cat5 jack)

[1]:https://en.wikipedia.org/wiki/Modular_connector

Many of these even now remain on dial-up, so they just have a modem and the cable is a phone jack. If you have a favorite bodega ATM that always takes 15 seconds to respond after you type your PIN, it's probably dialing. Newer ATMs almost certainly use wireless modems, if they aren't just connected to the Internet.

Fun fact, the modems still negotiate at 2400 or 9600 baud, because the extended negotiation times of higher-speed protocols more than negate time saved in transferring the small payload.

They even make gateways to bridge old dial-up ATMs to IP: https://atmpartmart.com/wireless-atm-modems/systech-box-ipg-...

Depending on the age it's either a Cat-3 cable or just a telephone cable in a round shield. It could also just be a serial cable.

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