International user registration via SMS

I've noticed a lot of mobile apps, specifically messaging apps, are switching from email verification to SMS'ed auth codes. Being based in the US, I am wondering how this works for international users. It seems illogical that users always receive an SMS from a US-based number.


Twilio Evangelist here,

We have a lot of people using Twilio for this, sending an SMS to the user with an authorisation code. I'm actually based in the UK, and I get them from all sorts of different numbers. Some companies use short codes (4/5/6 digit numbers), some companies use a regular long code number.

Unlike the US, we have mobile number ranges in Europe, so you can tell the difference between a mobile and landline number. Although UK landline numbers can weirdly send and receive SMS...

The experience is fine - if I've just completed some action on a web page or an app, I'm expecting the SMS, and I seldom even notice the number they came from. In fact, to answer this I had to look through my received messages to see what numbers were being used!

Hope this helps.

They probably use a company that aggregates messaging from many operators around the world. e.g.,,

But there's no reason they can't send it from the U.S only though. There is a chance that it is blocked as spam perhaps.

Need Your Help

onSomeEventListener crash

android android-fragments

I have set up an application with a main activity and 2 fragment activities. I use a onsomeevent to pass data from the fragment to the main activity. The first fragment works fine and passes data. ...

Zend 2 - Add validator and filter to custom form

php validation zend-framework2 zend-form-element zend-form2

I'm going bananas here. I created a simple form containing two fields. One is a text field, the other a textarea. The form looks great but I won't validate - no matter what I try.