How was Twitter able to send/receive millions of SMS messages for free?

Question

I'm working on an application that sends and receives SMS messages to and from its users. (Don't worry - it's not spam - every user of the app expects to send and receive these messages).

One key aspect of the app... If a user sends a message to the app, the app then sends that message out to every person on that user's "team". So, the app will be sending a receiving a pretty significant number of messages (I'm hoping for a few thousand users, and 5,000-10,000 SMS messages per day).

I've been experimenting with a number of options:

1. SMS to email
2. Connecting a mobile phone to my server
3. Contracting an SMS gateway

Option 1 is great, since it's free, but it's unreliable (apparently mobile providers queue these messages after SMS messages they can charge for, so they're frequently received late or lost)

Option 2 is also cheap, but the mobile phone can't keep up with the number of messages I'll be sending. Also, the mobile phone provider will consider this volume of messages excessive.

Option 3 is perfect, except that SMS gateway providers charge PER MESSAGE (usually $0.02-$0.06 per), which creates an impossible scaling problem. (Reminds me of the old business adage... "Sure we're losing money on every transaction, but we'll make it up in volume...")

So, long story short - how on EARTH did Twitter pull this off? They've been doing a similar thing (allowing users to exchange SMS messages with the app) since the beginning. Even if they negotiated an INCREDIBLE discount (say, $0.001 per message), they'd be paying an ENORMOUS cost to send the hundreds of millions of messages they handle.

Does anyone have any idea how they did this?

Worley

maybe twitter paid a lot of money but I'm sure they made profit in anyway. Like advertising, collecting information like phone numbers. Imagine sending/receiving millions of sms and just knowing the make and model of the mobile phones used by the user is worth a lot. You could sell this information to analyze who (age, sex, etc.) uses what kind of phone in which country etc. – Distillate

Twitter has grown into a juggernaut that MIGHT be making money by selling it's data. But for a long time, as I understand it - it was just a small pet project of a few people. Even back then, it was sending a HUGE volume of messages. I can't imagine they were paying hundreds or thousands of dollars per day to provide a free service with little forseeable revenue potential. Of course, I could be totally wrong... – Worley

An interesting question, but unfortunately not really programming related :\ – Aubreyaubrie

@Dan - I thought this was a programming question because I'm hoping that the answer isn't "Twitter negotiated some kind of deal with Clickatell", but rather, "Twitter built it's own SMS gateway using 'X'. Here's how they built it..." That said, if anyone else also feels like this is an inappropriate question - my apologies - I'll remove it. – Worley

Answer 1

After a bit of Googling, it looks like Twitter has simply been signing deals with cell phone companies in various countries. For example (Twitter blog post link spam incoming):

• Australia: http://blog.twitter.com/2009/12/sms-tweets-for-telstra-australia.html
• Indonesia: http://blog.twitter.com/2009/11/sms-for-axis-indonesia.html
• New Zealand: http://blog.twitter.com/2009/05/hello-new-zealand.html
• UK: http://blog.twitter.com/2009/03/full-sms-service-for-vodafone-uk.html

Some more details about SMS in general here.

Spokesman

I was really hoping to discover that the early Twitter team had BUILT something (that, potentially, I could learn from and maybe reverse-engineer). But so far, it sounds like they just negotiated good deals with the phone companies. Too bad. Nevertheless, this is a very helpful answer - thanks Bears! – Worley

This answer explains how Twitter managed itself AFTER it was pretty large. But, how did it manage in it's earliest days, before it was big enough to negotiate with those companies? Even in those early days, sending 10s of thousands of messages would have burned through an enormous amount of cash? – Worley

@Worley In the early days, Twitter SMS was USA-only. In the USA, cell phone companies charge the recipient for SMS. This means there are ways to send SMS for free in the USA - see Free SMS API – Jot