I found something strange that affects SMS in Canada. You can send the lower case text "secure communication", but it will never be recieved by the recipient. I am not sure if this behavior is reproducible outside of Canada. It might be a software defect, or perhaps there is something capturing the text and trying to interpret it as a command. The issue is more difficult to reproduce if both the sender and recipient devices are iphone's due to the default behavior of sending via iText.
I originally posted about this late last year . I intend to investigate this issue more deeply, but my time has been consumed by another more pressing matter. The original HN post links to my blog post . Originally I jumped to the conclusion that it was a case of censorship, but I backtracked on that because the issue is case sensitive. I would love confirmation if this is reproducible in other countries.
Consider the other cases - it could be something like an anti-spam system; back when MSN Messenger was a thing, it would abruptly close any conversations in which certain virus-related keywords were said (mostly including ".exe", which is how I discovered it), presumably in an attempt to stop them spreading.
Or it could be a bug - there have been plenty of these, from simple strings causing mass IRC disconnections, to eerie conspiracy theories (see "bush hid the facts", a conspiracy caused by a bug in Notepad).
Or it could just be a bit of debug code accidentally being triggered. This past week, I had to explain to some users why a website was talking about "DEAD BEEF". The reason was innocent (glitch in a web server config), but to the end user it was incomprehensible.
All that said, if you want to investigate further, it's simple to disable iMessage on iOS devices. If you go to Settings->Messages, there's a toggle for it.
On MSN Messenger, one way around swear words in your username/status was to use the ASCII equivalent for a letter, which would get skip the filter but render as the letter.
So I looked a little down in my chart and hoped that 0x7 for BELL would do something, but it didn’t.
But 0x0 for NULL would cause all members of your contact list to immediately sign out and back in ad Infinitum.
Thanks for pointing out an easy way to disable imessage on iphone. Apparently after doing that iphone defaults to MMS. It still might be best to just turn off data and wifi.
This reminds me of how, until just a few years ago (as late as 2016), people were wondering why you couldn't tweet the phrase "Get better".
It turned out that you can't tweet any phrase that begins with "Get" because... you guessed it, posting tweets from the web interface still shared backend code with the SMS-based system. So it would interpret "Get foo" as an API request to fetch tweets, not a tweet itself.
 Twitter was originally designed to work on dumbphones! You could text your tweet to 40404 and it would post for you, or you could fetch tweets by saying "GET chimeracoder" and it would fetch the latest tweets from user @chimeracoder.
Also seems to not deliver SMSs that contain other combinations with 'secure communication' within it.
'Hahahaha juice secure communication james'
'Not secure communication'
Having said that, this is not working for everyone. I am trying to gather data on this to figure out where the issue might stem from. Would you be comfortable disclosing the make/model and carrier service of the sender and receiver. If you would prefer, you may contact me directly with this information and I won't include your identity in the record. My email is linked in the header of the blog post. I also have a public key  if you feel so inclined to send me a secure communication :-P
I can't verify it is send over SMS or MMS though. In theory there's no reason for my cellphone to send it over MMS.
The exact word used: secure communication
The Google Android client is nice because it displays what protocol it is sending over. It is important to confirm that it is sent over SMS. Also, it is important that the words "secure communication" are sent in all lower case which I see that you did.
Thank you for taking the time to test this. If you are sure it is being sent over SMS then I will add your entry as an example where it can be both sent and received
I did it from my S10 to someone else A8.
from within the twilio API, via pure SMS (no imessage, etc.) to an iphone SE with a US Mobile (verizon MVNO) sim card.
Was sent from a US number to a US number.
Messages containing "secure communication" failed when sent by SMS.
Both are iPhones, but one phone had wifi and cellular data disabled to force the SMS failover.
I could get it to deliver US to US, though.
These are common problems for those that try to go “data-only” and sign up for a virtual SMS service: they can’t receive 2FA SMSs.
I guess the positive is that it’s hard(er) for a bad actor to pretend to be bigger than they are.
from: Freedom Mobile
to: Freedom Mobile
Mobile data: off
Side note: So cool to see so many Canadians on here!
If requested I can send SMS to USA numbers.
Yes please! Also, if you have US contacts that would be willing to test US-->US and US-->Canada that information would also be valuable and appreciated.
Please include as much of this information as participants are willing to provide:
- OS+version of mobile device
- if WiFi / data was on or off
- Carrier of sender / receiver
- exact text sent
Super busy now for a while...