[Cryptography] Signal hypothetical use case becomes practical since cellular providers have started censoring private text messages

erik erik at erikgranger.name
Thu Dec 30 08:55:38 EST 2021

Recently, I heard a very concerning thing: If you share this link via unencrypted SMS on t-
mobile, it won't go through:


I first attempted to send the link to myself. It did not go through. 

Just for a sanity check, I sent it through Signal. It did go through, obviously. 

I then tried to send it to myself again through regular sms. It did not go through. I tried 
sending the word "test". It did go through. 

I repeated several variations of this sort of behavior several times before sending a 
message to other people I know who I know use t-mobile. They did not receive the link. I 
then sent it to people who do *not* use t-mobile. They did not receive the link. Of course, 
sending the link through Signal did work. 

We started to develop pretty quickly a rough table of which mobile providers were 
blocking it and which weren't. 

Verizon does not block the link. AT&T does not block the link. Cricket Wireless does not 
block the link. One person said that Mint Mobile does block the link, and then another 
person who apparently also has this cellular provider I've never heard of said that the link 
was *not* blocked. 

We also determined that links to just the domain itself are blocked, so you can't just tell 
someone, "go to this link, click here, click there..."

Like teenagers testing out Runescape's cuss-filter, we had a doozie of a time trying 
random variations and seeing what worked and what didn't... but I stray from the point.

I believe this is interesting because it demonstrates, in reality, a concern that is always 
mentioned in terms of a hypothetical (at least in the USA). Very rarely does anyone ever 
have to confront the reality that their cellular provider can block and censor their text 
messages. If they do agree that it is possible, they usually do not agree that the cellular 
provider ever *would* do that. Now, we have a real case study, and if you have t-mobile, 
one you can demonstrate to them. 

This may aid in cryptographic communication adoption. As I said, of course if you send it 
through Signal it gets there no problem.

[1] https://www.canadiancovidcarealliance.org/media-resources/the-pfizer-inoculations-for-covid-19-more-harm-than-good-2/
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