I'm not suggesting another competing platform. I'm suggesting an already-widely-deployed platform (RCS) that is standardized, has been around since 2008 or so (older than iMessage!), and is the actual real elevation of SMS, not an Apple-proprietary protocol.
> If iMessage was cross platform
It's not, and that's the problem! Making it cross-platform would at least partially solve the problem, though it does mean Yet Another Messaging App I have to install.
> If you want secure cross platform messaging, use any of the other platforms built around that feature.
That's a huge pain in the ass. Not all of my friends have Signal, and I'm tired of evangelizing. Not all of my friends have WhatsApp, and I'm not interested in evangelizing a Facebook property. I don't use Telegram, and very few of my friends do, and I'm also wary of evangelizing a messenger that is not secure by default, and that has what is IMO a sketchy, secretive history around its cryptography.
Looking through my Messages history, there are 27 people I communicated with over unencrypted SMS/MMS over the past month. Only one of those people has Signal (not sure why they SMS'd me, but that just further illustrates the problem of how it's difficult to remember to contact people using the "correct" means), and maybe 6 or 8 of them have WhatsApp (for whatever reason, they/I don't really use WhatsApp often).
Why is this so hard? Apple! If Apple supported RCS (with the E2EE extension), literally every single one of those 27 conversations would have been encrypted, without me (or, critically, the other party, whom I have no control over) having to do anything special. As much as I love blaming Google for many things, they cannot solve this, because iMessage is a closed protocol that they are not permitted to implement, and the messenger app that is in the default install (the iMessage-supporting Messages app on iOS, and the RCS-supporting Messages app on Android) has a huge easy-adoption advantage that third-party messengers will never be able to match.
You can argue a bunch of "shoulds" here, but I'm talking about what the reality actually is.
The RCS Universal Profile is the first standardized version by the GSMA and came out in late 2016.
Google's RCS usage has primarily been via Google's own hosted implementations because of poor carrier adoption. Verizon AFAIK is planning to have RCS deployed this year.
Also AFAICT the e2e extension is not a standard but is Google-specific and currently exclusive to their Messages app. It also has several inferior technological, privacy, and UX impacts to other systems (such as only working for 1-to-1 chat, or requiring out-of-band verification code comparisons to guarantee the encryption isn't compromised).
It also is not a protocol evolution of SMS - its similarity is mostly that it like SMS was standardized through the GSMA. I also do not believe that the GSMA mandates its usage "instead of" SMS - it is meant to sit alongside SMS.
> That's a huge pain in the ass. Not all of my friends have Signal, and I'm tired of evangelizing. Not all of my friends have WhatsApp, and I'm not interested in evangelizing a Facebook property.
There's zero chance that RCS will replace Signal or WhatsApp or Telegram. It also won't replace SMS, at least this decade. It's just going to be Yet Another Option.
They are likely using an Apple device, so they can't use Signal as the default SMS/messenger app and have to remember to use it for the right contracts.
Android allows you to choose the default messenger app, and setting up Signal this way gives you an experience very similar to the iMessage one on Apple devices - messages to non-Signal-using contacts go over SMS/MMS, messages to contacts with Signal go over the Signal protocol.
Signal supports SMS on Android because Android has API for apps to actually interact with the underlying phone SMS capability (because Android is a platform customized by OEMs).
Apple does not have public API to interact with the hardware to send/receive SMS, although there's no limitation on using SMS in other apps.
There are two messaging limitations in the platform:
1. The sms: url scheme can only go to the built-in app. Since this does not let you pre-compose messages, I've actually never seen it used in production.
2. The MFMessageComposeViewController is used to overlay iMessage with your application to send a chat message. Generally I've only seen this used in lousy applications (admittedly including Twitter and various Google applications in that list) - the modern approach is to use the Share and Action sheet functionality, which presents first and third party apps via equal heuristics.
People are advocating for the opposite. Make apple stop using their anti-competitive market to harm alternative messaging apps.
> If iMessage was cross platform, it’s just another messaging app.
No, it is just as good, and better if it is forced to be cross platform.
You lose nothing, and everyone else gains, when anti-competitive markets are made to support alternatives.
> If you want secure cross platform messaging
Or, instead of that, we could use anti-trust law, against Apple to force them to be less anti-competitive, and allow other people to integrate with it. Problem solved.
I love how it's such an anti-competitive market that in many countries Apple isn't even close to being a popular service. WhatsApp, WeChat, Kakao, Line etc dominate in non-Western countries.