Why does my SMS Two-Factor Authentication fail?

January 29, 2021 10:26 AM

Hi ALl, I ported my cell number over from a previous carrier the other day, and things seem to be going well, apart from one issue. I don't get SMS-based 2FA codes, at least not from Paypal. Other people can seemingly text me just fine, and I can text them as well. What gives?

Paypal is particularly annoying as I need to use them on a semi-regular basis, and while the mobile app works it isn't as full-featured as I'd like. When I ask for an authentication code it just sits there, acting as if one has been sent, but it never arrives.

I can click a link about "having trouble?" to try and log in another way, but it just runs me through the same SMS loop again. There's no option to email me a code, which I could receive perfectly well.

Any insight into what's going on would be appreciated.

posted by Alensin to Computers & Internet (7 answers total)

Do you use an iPhone? Is there any chance you are not receiving any SMS at all, but only iMessage?
posted by kickingtheground at 10:35 AM on January 29, 2021

Response by poster: I do use an iPhone. I'm definitely receiving SMS/text messages from other people who don't use iPhones, sadly.
posted by Alensin at 10:39 AM on January 29, 2021

Maybe you're having trouble receiving text messages from short code numbers? Apparently some carriers don't support them, or don't support them by default, according to this: Why Can't I Receive Short Code Messages? The article refers to a list of carriers that do support short codes but doesn't link.

You could try signing up for texts from a retailer or charity maybe to test it out. (Bed Bath and Beyond is the top one in my messages right now: number is 239663 and you can test by texting "help".)
posted by mskyle at 10:54 AM on January 29, 2021

It almost sounds like your porting process isn't completed. While the voice portion was ported, the SMS portion wasn't.

I personally prefer NOT to use SMS authentication, but instead, use an authentication app like authy which generates OTP (one time pad) numbers based on your identity and a timestamp, so they can't be intercepted.
posted by kschang at 10:59 AM on January 29, 2021

Do try following up with your new carrier. I had this problem and they had to reset something on their end to get short code messages working again. (The first time they 'reset' things it made no difference and I thought I was SOL. A few months I heard from someone else who was able to get the same thing resolved, so I tried them again and this time their reset actually worked.)
posted by trig at 11:22 AM on January 29, 2021

Could this (not sending 2FA codes to recently-ported numbers) be a fraud-prevention measure on the part of PayPal? Maybe something to ask your new carrier.
posted by heatherlogan at 11:34 AM on January 29, 2021

Response by poster: Hey all,

Welp, I did a "network settings reset," on my iPhone, and that seems to have resolved whatever weirdness was going on. The short code messages are coming through just fine now.

I definitely try to use authentication apps whenever possible, but it doesn't always seem to be, depending on the site. Glad this is resolved for now, even if i'm not sure why.
posted by Alensin at 11:51 AM on January 29, 2021