Email to SMS gateways are good for one purpose and one purpose only: creating a notification for your own personal use, whether for a script, an external service that can send emails and you want an SMS instead, etc.
They should not be used for any production application. But they are, and by some companies that should know better or at least be able to afford an actual SMS-sending service.
It's obvious when an application is using an email to SMS gateway; they'll ask for your phone number and then also have you select your mobile carrier. If they're using a full-fledged SMS sending service, they won't need to know your carrier.
This is a result of how email to SMS gateways work. If you're not
familiar, using one of these gateways is as simple as sending an email to
number is the phone number
of the recipient, and
xyz.com is the
carrier-specific gateway email address. For example, AT&T
txt.att.net, Verizon uses
tmomail.net. You have to select your carrier so
the application knows what gateway to send to.
This is the problem - there are way more carriers than anyone can be reasonably expected to support, especially when one considers all the regional and prepaid carriers that exist. If you're outside the USA, I have no idea what the email to SMS gateway situation is. It might not be supported at all internationally, so applications using these gateways are even less accessible.
The issue of too-many-carriers is exactly the problem I've run into. I couldn't get an SMS for my tire installation appointment because my prepaid carrier isn't on the list of available carriers. When I went to college, one of the dining places on campus sent an SMS when your food was ready, and that was the only notification method. So when I used a small regional carrier at the time, which obviously wasn't available in the select-your-carrier dropdown, I was SOL and usually had to ask a friend to let me punch in their phone number so they'd get the notification and could let me know.
These email to SMS gateways are great if you're creating a script or application for your own use that you want to send you an SMS on certain events. However, they are a terrible option for any production service, unless you are 100% certain that all of your users will be using only the carriers you specify in your carrier selection (spoiler alert: they won't be).
Originally published December 10, 2019. Last updated December 10, 2019.