Mobile carriers in many countries provide a free email→SMS gateway service, so if you have no SMS capability or credit, or you are outside the country you can still get an SMS to someone using just email.
I had a look at many SMS gateway lists¹, and Base/Telenet and Proximus are never mentioned. Orange has no Belgian gateways, just:
Doing an MX lookup on @sms.orange.nl
gives nothing, so the service to Dutch subscribers has apparently been unplugged.
Orange claims to support RCS (Rich Communication Services) exclusively for Android 8.1+ devices. Yet wikipedia shows the Orange service to be discontinued… that it only lasted 2012-2019.
OTOH, an article (fr) claims all 3 carriers (Base, Orange, Proximus) deploy it around 2020.
English translation:
The three Belgian mobile operators officially have an RCS infrastructure. For Android smartphone users, this SMS 2.0 becomes an interesting alternative to private online messaging. The data will now be fully managed in Belgium.
Telenet today announces support by its BASE mobile subsidiary of the RCS, Rich Communication Services. Orange Belgium and Proximus preceded it successively in November 2019 and August 2020. Now, the three competitors have deployed the Belgian variant of this service largely pushed by Google. Indeed, the American giant, tired of waiting for the operators to get there, had announced a progressive and global deployment on the Android park. Good news therefore for BASE customers, using Google Messages, their data will no longer transit through Google but through Telenet’s infrastructure.
As a result, in Belgium, the RCS becomes a very interesting alternative to WhatsApp, Facebook Messenger and others. If, and this is where the bait hurts, all the participants in the conversation exploit an Android smartphone. Under iPhone, your messages will be displayed as vulgar SMS. Note, for most Samsung, it will be necessary to download Google Messages which is usually not installed by default. On the Huawei side, if Google Play Services are absent, the service will not work.
Finally, Telenet draws its customers’ attention to pricing. Indeed, we must be careful with the international. Sending text messages abroad remains expensive. It is therefore valuable to check that the content is transiting through the RCS protocol.
Indeed that’s absolute fucking garbage that all parties to the conversation must have an Android -- in effect: SMS 2.0 is only for Google patrons. RCS is touted to be an open standard alternative to walled-gardens. But f-droid.org has no RCS app. Nor does Debian.
So, RCS can fuck off. Are there any old email gateways for Belgian GSM subscribers that are perhaps widely unknown?
Orange has this roughly explained service:
https://easymessaging.orange.be/
So you cannot simply send an email. You must register. And registration demands a mobile number (needed because the SMS callerID will be “spoofed” to your number). It does not state whether your own mobile number must be an Orange number. So it’s unclear if senders must be an Orange customer, and it’s also unclear if the recipient must be an Orange customer (though unlikely because you cannot know easily what carrier the recipient uses).
For me, it’s broken. I could not get past the verification step. If anyone else attempts it and succeeds or fails with that, feedback would be appreciated.
① Link farm of SMS gateway lists:
https://www.email-unlimited.com/stuff/send-email-to-phone.htm
https://when2work.com/help/emp/find-text-address/
https://gist.github.com/spangey/518e358959e545bf03fc
https://helpcenter.horizonwebref.com/en/articles/6221095-what-mobile-carriers-do-you-support-for-free-text-messaging
https://web.archive.org/web/20241213132316/https://www.lifewire.com/sms-gateway-from-email-to-sms-text-message-2495456
https://avtech.com/articles/138/list-of-email-to-sms-addresses
https://20somethingfinance.com/how-to-send-text-messages-sms-via-email-for-free/