Yahoo Groups is about to shut down, and it’s taking a lot of the old web with it. All content that had been posted there will be deleted by mid-December, and although it will be available for download before the end comes, the site will be largely shuttered by the end of this month.

Because Yahoo didn’t give the internet much warning, a lot of weird externalities of the company’s decision are being worked out in public. One that’s particularly surprising: the United Kingdom’s phone system actually relies in part on a Yahoo group founded in 2002 — which I learned about through a tweet.

“A review might consider whether it is befitting for the world’s sixth largest economy to manage critical national infrastructure via a Yahoo group but we would hope that is obvious,” reads the 2015 report referenced in the tweet, which was prepared by Simwood, a UK telecom, and sent to Ofcom — the UK’s national telecom regulatory body.

Ofcom, otherwise known as the Office of Communications, is analogous to America’s Federal Communications Commission. One of its roles is to manage telephone numbers in the UK. The organization allocates numbers in blocks of 10,000 to telecom companies, which then activate the numbers for use on their networks. Ofcom maintains an official database of those numbers on their website, which is available to the communications companies.

Ofcom isn’t really involved with the Yahoo page itself, according to an organization spokesperson who wasn’t authorized to speak on the record. The group is an informal way to tell other telecoms who has which numbers, they said, which is important because that determines how calls are routed and charged. Basically, Ofcom’s position is that the group is unnecessary because they maintain their own database that’s regularly updated with all the info that telecommunication companies might need.

But the Yahoo group may still be necessary to companies in the industry. Simon Woodhead — the CEO of Simwood, which wrote the 2015 report — said that the Yahoo group is useful for letting telecommunications companies know how those ranges of numbers have been distributed.

Apparently, there’s not really a better way to let UK phone providers know which numbers belong to their competitors. “They would say the group is informal for operators to talk to each other and there is a database for managing numbers. That is correct, but slightly evasive,” Woodhead said. “If you were to ask them what the formal process and means for operators to announce active number ranges to each other is, they wouldn’t have an answer because the answer is the Oftel Yahoo group.” (It’s known as the Oftel Yahoo group because Oftel — or the Office of Telecommunications — was the organization that preceded Ofcom, and the Yahoo group precedes the creation of the UK’s communications regulator.)

Essentially, Ofcom manages the numbers that telecom companies like Simwood can get; they build those blocks of numbers that they have on their network, and afterward need to tell other telecom companies that those numbers that they received are ready for service, and where those numbers can be reached. This, Woodhead said, gets essential when you’re talking numbers because you need to know where the numbers are. Simwood hosts number ranges for other operators, which is a problem because “nowhere in Ofcom’s database is that relationship recorded.”

Operators need to know where those numbers are hosted so they can route calls to them. “That’s the purpose of the Oftel group,” says Woodhead. “So we say ‘Hey, this range from Fred Bloggs Limited is now live on the Simwood network. These are the points of interconnect on the BT network. If you’ve got a bilateral with us then talk to us directly. And by the way, this is the test number.”

The Yahoo group is also important because operators need to know how much to charge consumers for calls, because it’s not obvious from the number range itself what the rate is going to be. The group facilitates that, by allowing operators to tell each other to update their rate sheets.

Woodhead likened the Yahoo group to DNS, the Domain Name System, which is the internet system that associates information like IP addresses with domain names. “Like, www.theverge.com points to a given an IP address,” he said. “What the Ofcom list does is say that “theverge.com” has been registered. What it doesn’t do is say what the IP address is.”

The internet has its own protocols to make that happen. Voice communications, on the other hand, do not, which is where the Yahoo group comes in. “It says hey: theverge.com is now active on our network and this is the IP address.”

The idea that at least some part of the UK’s voice communication infrastructure rests on the framework of Yahoo Groups feels a little alarming; shouldn’t phone numbers be easier to manage than the internet? But then: the infrastructure that underpins the stuff we use and take for granted every day is usually far weirder and more complicated than it seems at first.

Yahoo plans to delete all of its uploaded group data — which includes files, photos, attachments, email updates, and message history, among other stuff — on December 14th. That may not entirely disrupt its usage by UK telecoms, though, as email functions are still supposed to work.

“My understanding is that [the group] will still function as a mailing list, which is for all practical purposes, what people use this as,” Woodhead says. “But quite frankly” — and here he scoffs — “the world’s fifth largest economy, or whatever we are now, relying on a Yahoo group to administer critical national infrastructure is embarrassing.”

https://www.theverge.com/2019/10/17/20919630/yahoo-groups-uk-ofcom-simwood-numbers