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Comment by pricechild | Hacker News Reader

> 1) AT&T started blocking any number permanently across its network last January if it contains a hyperlink or email address, even if the customer interacts with the number. I had to create separate messages just for the 12.5% AT&T users.

I don't follow - they blocked any number which replied with a hyperlink or email?

Can users of AT&T not send them to each other?

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If you send a message containing a hyperlink or email address from a Twilio number to an AT&T number, AT&T will block that Twilio number across its network without any notification. This happens even if you have an ongoing thread going with the customer. Even if after the block happens the customer pings the bot with "START" or any message, AT&T silently ignores it and continues to block the number. The customer can continue to send messages inbound to the number (and I believe those get received by Twilio but can't quite remember) but any outbound responses are blocked by AT&T from making their way to the customer, even though they're marked delivered by Twilio. This was the case as of Feb 2019. It could've changed since then and I haven't checked recently.

I bet that AT&T can detect "non-real-user" phone numbers, so their hyperlink filter only acts on those numbers.

I have been using Google Voice as my secondary phone number for the past 5 years, and some services manage to detect that it isn't a real phone number and refuse to work with it. More specifically, it usually happens when I try to use 2FA over SMS (note: i know that 2FA over SMS is not considered secure, but some of the services I use only offer this as their 2FA, and it is better than me not using 2FA at all). It doesn't just fail to deliver the message, the service straight up tells me to enter a "real" phone number.

I've noticed this as well. Services like Twilio provide an endpoint to check the carrier. For my Google Voice number, they return "Google (Grand Central) BWI - Bandwidth.com - SVR."

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