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29 Nov 2022
The usually perceptive Tim Harford has a column in the current Financial Times complaning that since he can move his phone number from one carrier to another, why can't he move his social media account from Twitter to Mastodon. If only it were that simple.
Phone numbers are portable because phone service is completely standardized and heavily regulated, neither of which is true of social media. Phone numbers all have the same form, and are handed out in blocks by governments. Your mobile phone account can only do three things: phone calls, SMS, and IP data. Everything else is either in the phone, like your contact list, or is done in some custom proprietary way. Phone numbers are not portable because telcos wanted them to be, they are because governments forced them to do it. Every time you make a phone call, the number you called is looked up in a shared database which tells which carrier currently handles the number, and the call is routed to that carrier. All carriers use compatible protocols and are required to be able to deliver calls directly or indirectly to all other carriers, and all carriers have roughly the same business model, charging users to use the service. (For more details on how portability works see RFC 3482.)
On social networks, everything is proprietary, there is no mandatory interconnection, and often things that look similar on the surface are not underneath. User identifiers work differently, the sorts of things an account can post differ (plain text, formatted text, images, video), the ways they can react to or refer to other posts, and most importantly the way the social network decides what messages to show to which users.
Mastodon is often seen as an alternative to Twitter, which it sort of is, but it is also so different internally that it makes no sense to talk about moving a Twitter account to Mastodon. Twitter is a single centrally controlled service, while Mastodon is a large group of independent hosts communicating with a shared protocol, each of which manages its own accounts and its own policies. It's sort of like the way e-mail servers work. It's not a coincidence that Mastodon account names look like e-mail addresses, a name at a server.
In an imaginary world with portable social media acconts, if I move from Twitter to Mastodon, there'd have to be some way to link my old Twitter account to my new account since Twitter account names are not the same as Mastodon account names. That might make Twitter forward anything sent to my old account to the new one somwehere else, or by an external database lookup, similar to the way phone calls are routed. Both have problems; the first lets Twitter see and potentially mess with your traffic forever, the second doesn't exist.
Far worse, though, is the problem of followers. The list of people you follow belongs to you, but the list of people who follow you does not, it belongs to each of them. (If you could take a list of putative followers and tell Twitter or some other site to send a message to all of them, that would be a giant gift to spammers.) Mastodon handles this in a fairly brute-force way--each account notifies all the accounts it's following, every time you publish something your server sends a copy to each host it thinks has some followers, and the followers' servers decide what to show. This works OK at Mastodon's scale, but it would be a challenge with the millions of followers that popular Twitter users have, not to mention the extra complication when someone moves from one place to another and has to update their followers and followees.
While it's sort of possible to imagine a scheme that does more or less what Mastodon does at a larger scale to connect to Twitter, and maybe other social networks (what does it mean to move from Twitter to Instagram?), it would be a great deal of effort, way more than just changing the switch a phone call is sent to. The security issues to keep it from enabling a flood of spam and abuse would be daunting. None of it exists now, and even if it existed there is no reason for any existing social network to participate if it made it easier for people to leave.
By the way, for anything beyond the three standard services, mobile phone accounts are no more portable than Twitter accounts. Look at voice mail. Every phone acount has it, but if you want to take your annountment or saved messages with you when you switch carriers, too bad. The contact list lives in the phone, these days invariably backed up to Apple if you have an iPhone, or to Google, if an Android. Switching from one to the other is painful, involving third party apps or a lot of retyping, and your mobile carrier doesn't help.
Earlier this year the European Union decided to require that instant messaging services interconnect. This is a much easier problem, no portability of accounts from one service to another, and just sending individual messages, no swarms of followers to keep track of. Nonetheless it will be a major technical challenge, with many of the same security and spam problems (do you really want to let random Gab and Parler users send messages to any user on any other system?) and I'm watching with interest to see if and whether it actually comes to pass.
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