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1. POTS aims at "5 nines" reliability. [1] 2. > the chances of them all being down at once is far lower than your POTS line being down. That depends crucially
by FabHK 7y ago
1. POTS aims at "5 nines" reliability. [1]
2. > the chances of them all being down at once is far lower than your POTS line being down.
That depends crucially on the correlation. If there are common fault modes (such as: internet down), the probability might be way higher. (Remember, it used to be common wisdom that it was possible that one or two home owners won't be able to pay their mortgages, but the probability that many will be unable to pay their mortgages is so low that all these MBS and CDO's can be rated AAA...)
3. EDIT to add: Of course, adding communication options can only increase the probability that you can reach your emergency provider, but there's a reason that Skype etc. used to come with these big disclaimers that they're no replacement for POTS, namely the excellent reliability of POTS.
[1] "Although POTS provides limited features, low bandwidth, and no mobile capabilities, it provides greater reliability than other telephony systems (mobile phone, VoIP, etc.). Many telephone service providers attempt to achieve dial-tone availability more than 99.999% of the time the telephone is taken off-hook. This is an often cited benchmark in marketing and systems-engineering comparisons, called the "five nines" reliability standard."
https://en.wikipedia.org/wiki/Plain_old_telephone_service#Reliability https://en.wikipedia.org/wiki/Plain_old_telephone_service#Re...
- slfnflctd 7y agoThis is exactly the reason why I find all the gleeful tearing out of old POTS copper lines very distressing. This was a proven system with incredible reliability, which worked in power outages for residential users due to centralized backup systems, and still has plenty of usefulness. Until we come up with some universal multi-layered standards which provide at least the same level of uptime and utility, it seems more than a little premature to pull all of it up as a matter of course. Obviously in many places there are space constraints, but that is not usually an issue in arguably the most important use case, at home.
- walshemj 7y agoBetter that Five nines - experiencing a major switch failure should be something you experience once every two or three generations.
- londons_explore 7y agoIn the UK, BT phone lines go down (cut existing calls) for about 5 minutes about once a week between 2am and 3am... I'm guessing some software update?
- londons_explore 7y agoI would argue that in the real-world, for emergency use, POTS only has ~60% reliability. When an emergency happens, what are the chances a POTS phone is nearby? If there isn't a landline within 100 yards of the incident, the POTS network has failed to help. Now given that, does it really matter if the actual phones have are "3 nines" or "5 nines"?