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Getting Started with Twilio SMS - Ideas, Resources, and Motivation

On Tuesday, we announced our newest product, the Twilio SMS for programatically sending and receiving text messages with your Twilio phone numbers.  We've also got a developer contest running this week that we'd love to see you get involved with.  For almost a year, we've been giving away a Netbook each week (and sometimes even more than one!) to the best app developed in different categories.  In honor of our SMS launch, this week's category is SMS.

The use cases for SMS range from the obvious to the wild, so whatever you want to build to kick the tires we're excited to see your submissions.  Keep in mind that they're due by Sunday, February 14th at 11:59pm and you can submit here.

Ideas for Your First Twilio SMS App

With Twilio our goal has always been to make it as easy as possible for developers to integrate our API into their applications.  In fact, if Twilio is just 5% of the technical guts of your application that's great - it means we're doing it right.  So whether you have an application you've been aching to add SMS to, or have the time and motivation to build something from scratch, we encourage you to get involved.  Here are a few app ideas we'd love to see:

• * automated SMS alerts when a new blog post comes into an RSS feed
• * SMS birthday reminders for your Facebook friends
• * group text messaging like Betwext, the winner of our SMS beta contest
• * location based games
• * turn by turn directions (not sure how you'd pull this off, but would be cool)

Steve Poland also wrote a blog post yesterday brainstorming a list of Twilio SMS App ideas that you might find helpful.  If you're looking for other APIs to mashup Twilio SMS with, make sure to check out Programmable Web.

Resources to Get You Started with Twilio SMS

We've got tons of resources to help your adoption of Twilio SMS go smoothly.  From technical documentation to conceptual explanations, we've got you covered.  If we've missed anything and you've got questions, please drop us a line at help@twilio.com - we're always listening.

• Twilio SMS Quickstart
• How To: SMS Notifications
• How To: Send SMS From Inside a Phone Call
• Receiving SMS: <SMS> TwiML Documentation
• Sending SMS: Twilio SMS REST API Documentation

Read More About the Launch of Twilio SMS

• TechCrunch: Twilio’s Telephony API Now Lets Applications Send And Receive SMS Messages
• GigaOm: With SMS, Twilio Continues to Shake Up Communications
• VentureBeat: Twilio adds SMS text support to its phone-to-Web API
• Albert Wenger of Union Square Ventures: Twilio
• Fred Wilson's "A VC" Blog: Twilio

Introducing Our Ridiculously Simple Twilio SMS API

Update: This week's developer contest category is SMS.  Build a Twilio app using SMS and submit by midnight on Sunday, Feb 14th for your chance to win a Netbook.  More details on the contest page...

Today we're excited to announce the launch of our newest product: Twilio SMS.

Existing customers already know you can use Twilio to make and receive phone calls, and now you can also send and receive text messages from your Twilio phone numbers!  Starting today, all local Twilio phone numbers are SMS enabled, allowing you to write SMS applications as easily as you can write voice apps on Twilio.

We're ridiculously excited about Twilio SMS.  Previously, building SMS apps was hard... it could take months of negotiations, approvals, and hundreds or thousands of dollars up-front and every month to get started.  With Twilio SMS, it's as easy as buying a Twilio phone number from the Twilio account portal or Phone Numbers REST API for $1 / month, and immediately start receiving and sending text messages using Twilio's SMS REST API for just 3 cents per message.  No waiting period, no contracts, no hefty up-front costs... just $1 and your imagination.

Also, Twilio SMS is fully integrated into Twilio's voice functionality.  Need to send an SMS from inside a phone call?  Just drop our newest TwiML verb in there: <Sms> and Twilio will send a text message to the caller with whatever content you specify. 

For example: <Sms>Our hours are 9-5</Sms>

Get Started with Twilio SMS

Are you ready to explore the power of Twilio SMS? It's incredibly simple to start adding text messaging to your existing Twilio applications and web applications, and we've got the tools to help you get started:

• Introduction to Twilio SMS
• Twilio SMS Quickstart
• How To: SMS Notifications & Alerts
• REST API: SMS Documentation
• TwiML SMS Documentation

Customer Story: Salesforce.com

DreamForce 2009 was the biggest Salesforce conference yet, and when Salesforce.com needed to allow the 19,000 attendees to vote for the "Best in Show" Appy Award, they turned to Twilio SMS.

Their app received and tallied votes from the participants and responded in realtime with SMS confirmations.  With Twilio SMS and the Force.com platform, Salesforce developers only needed a few hours to build an app that scaled to Dreamforce-proportions.   

Read about how Salesforce used Twilio SMS at Dreamforce >>

Phone Number Price Reduction

We're also happy to announce that we are now able to lower the prices on all Twilio phone numbers.

Starting today, all local numbers are $1 per month, and all toll free numbers are $2 per month.  By aggregating the demand of many applications, we're able to lower costs for all Twilio customers... and now we're excited to see what applications are enabled by these improved phone number economics. The new pricing is automatically applied to your Twilio account, and you'll be charged the new prices next time your phone numbers renew.

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In the coming weeks we will expand our blog coverage to focus on Twilio developers using our new SMS API and we would love to hear about what you are building, and feature it here.  As always, if you have questions or concerns please feel free to contact us at help@twilio.com with questions, comments, and blog post ideas.  We're always listening and ready to help.

Announcing Ridiculously Simple Conference Calling

We're excited to announce the release of a new Twilio feature: Simple Conferencing!  With the addition of <Conference>, you can bridge together multiple inbound or outbound calls, opening all new possibilities. 

Sick of those crappy conference lines?  The ones that that require you to enter your conference id, participant pin, access code, weight in kilograms and pi to fourteen digits before you can get to chatting?  Now you can build your own with just a few lines of code.  Ready?

How Conferencing with Twilio Works

Twilio conferencing adds new REST and TwiML elements to allow bridging two or more in-progress call sessions.   Just <Dial> a <Conference>, and specify the name of the "Room"... any callers who dial the same room will be conferenced together... it's that easy!  Check out these ideas:

Simple Conferencing

Create a simple conference call in just a few lines of code.   By default, we take care of all the niceties... playing music while the first person is waiting, playing the "ding" when people enter and leave, and more.  

Check out the Simple Conference Call How To now to start building.

Moderated Conferencing

For larger conferences, it helps to have a call "moderator" to determine when the conference starts and ends.  By explicitly specifying the "startConferenceOnEnter" and "endConferenceOnExit", you can determine who's in control. 

Callers who are not moderators will hear hold music until a caller with startConferenceOnEnter='true' calls into the conference line.  

You can also drop participants into a conference muted, and later mute, unmute or kick participants via the REST API in realtime.  You're in control.

Check out the Moderated Conference How To to get started!

Call Holding

In addition to building traditional business conference lines, a <Conference> is also useful for keeping one caller on "hold" while waiting for another caller to join.

Let's say a customer calls to speak with an operator or customer service agent. Drop them into a <Conference>, and let the hold music roll.  When the agent is available, <Dial> them into the same <Conference> to start the conversation.  You can also specify that when the operator leaves, the first caller should be sent on her way.

Are there features you'd like to see added to Twilio in the future?  Fill out our the Twilio Features Wishlist to share your opinion, and we'll notify you with any updates about features you've requested.

Call Redirection via the Twilio REST API

Twilio is excited to announce the addition of asynchronous call redirection to the Twilio REST API.  This feature opens a wide range of advanced call queuing, call center, and enterprise uses.   Using the call redirect API, you can interrupt an in-progress call and have it begin executing a new TwiML document of your choice, simply by POSTing to the Call Instance Resource.

This API gives you realtime control over running calls.  You can put calls in and out of hold music,  transfer a call from one <Dial> to another, hangup a call and so forth - all by making a simple REST API request.

Placing the Caller on Hold

Here is a simple example:

Lets say you receive an incoming call and want to put the caller on hold until someone can answer.  You can simply drop them into a TwiML document like this:

<Response>
<Say> Thank you for calling, a representative will be with you shortly</Say>
<Play loop="100">http://www.mydomain.foo/hold-music.mp3</Play>
</Response>

The caller will sit in a loop of hold music, patiently waiting.

Taking a Caller Off Hold

When a representative becomes available or other external event to occurs, your Twilio application can issue the following REST API request:

POST https://api.twilio.com/2008-08-01/Account/{YourAccountSid}/Calls/{WaitingCallersCallSid}
CurrentUrl=http://www.mydomain.com/dial-representitive

This will interrupt the looping Play verb and begin executing the following "dial-representive" TwiML for the caller.

<Response>
<Dial>415-555-6666</Dial>
</Response>

The end result is that the caller has been removed from the <Play> loop and placed into a <Dial>, taking he or she off hold and connecting the call to the representative at 415-555-6666.

Hanging Up on the Caller

If instead you wanted to hang up on the caller, you could make a similar REST API request which redirects the call to this TwiML document:

<Response>
<Say>Thank you for calling.  Goodbye</Say>
<Hangup/>
</Response>

Simple as that!   For more information on this feature, see the "Redirect a Call" section of the REST API documentation. We also have example code for a simple call queue in our HowTo section.

Month in Review: Looking Back at August

We're already well into September, but for those who've just joined Twilio or only recently started reading the blog I thought it would be fun to give you a rundown of August - which was a busy and exciting month here.

Customer Profile: The Kingdom app adds Twilio to their alternate reality game for the iPhone, and Derek Neighbors from Held demonstrates how it works in this video

Twilio CEO Jeff Lawson speaks on the Cloud Computing Show with Geva Perry and host Gary Orenstein about cloud telephony, the platform-as-a-service model, and more.

John Tegen Wins Netbook Week #12 with Onsite Clarity using PHP and Adobe Flex to build this sales management tool.  (watch video)

Customer Profile: Ylastic announces that Twilio-powered voice alerts for their cloud services management platform are now available. (watch video)

Feature Update: International Oubtound Calling enters private beta for a select group of Twilio developers to test and provide feedback

Robert McLaws Wins a Netbook for the .NET Framework with his WCF Client for .NET 3.5

Feature Update: HTTP Authentication Twilio users can now access password protected URLs with the Twilio API.

Zeus Software publishes an article on how to voice enable their traffic manager tools using Scala and Twilio.

Customer Profile: Valley Curbside Recycling  Ryan Stewart tells us how he uses Twilio to power the company telephone with 20 lines of code.

Twilio Winners Announced for Interactive Advertising Contest Category ExcitementLivesHere.com and AdGames each take home a Netbook for their fantastic interactive ad creations

Pivotal Labs welcomes Twilio CEO Jeff Lawson to speak on cloud telephony and we streamed live on TwilioTV

Twilio-powered EscapeMyDate (lead by Danielle) wins most votes at Startup Weekend San Francisco for their integration of Twilio and Twitter for getting out of awkward social situations

Two winners awarded Netbooks for the Twilio + Amazon Web Services contest category: Email Center Pro by Evan Coonrod & Ask-a-Human by Eugene Osovetsky

Netbook Contest partnership announced with Microsoft Windows Azure with extended deadline of September 13th, giving developers two weeks to win a Netbook with a Twilio app built on Azure

September - Off to a Great Start!

Twilio exhibits at ITexpo West in Los Angeles, CA where we had a chance to mix and mingle with professionals in the telecom industry, and learn more about the vision for unified communications, which was the resounding theme of the event.

Highlighted Events in September

Gov 2.0 Expo Showcase & Summit

GigaOm's Mobilize: Future of the Mobile Web

SF NewTech

Seattle 2.0's Startup Day

Twilio Office Hours

Join us every Thursday from 4-7pm on IRC at at Twilio HQ to learn more about what we do, ask questions, and meet members of the Twilio development community.  We almost always on IRC, but this is a time dedicated to support from the Twilio team.

Interested in seeing more events where we'll be speaking or attending?  Check out our events calendar for a complete rundown, we keep it updated and you'll find everything from conferences to hackathons to networking events.  Check it out...

Twilio International Outbound Calling Now Available to Everyone

This has certainly been an exciting week for the Twilio team, which includes exhibiting at IT Expo in Los Angeles where we're spreading the word about the Twilio REST API and the power of telephony in the cloud, and partnering with Windows Azure for our developer contest (now with an extended deadline), and we've also got exciting news for the Twilio developer community.

Twilio International Outbound Calling - Available Now!

Twilio's International Outbound calling service, which was released with limited access to developers as part of our early developer access program, is now publicly available.  Now any Twilio developer can enable their application to make calls to hundreds of destinations worldwide from the account panel, with granular controls for each country and rate group.

How to Find an International Rate from Twilio

How to Configure Your Twilio Account for International Calling

Please give Twilio International Outbound a try, and thank you to everyone who participated in our early developer program with great feedback, and creative use cases!

HTTP Authentication for Twilio - Access Password Protected URLs

If you've tried to host your TwiML files at a secure URL, you already know that in the past Twilio only supported GET and POST to publicly accessible URLs.  But no longer!

New Feature: HTTP Auth with Twilio

Now Twilio supports HTTP Basic and Digest Authentication.  This allows you to password protect your TwiML URLs on your web server, so that only you and Twilio can access them. You may provide a username and password via the following URL format.

https://username:password@www.myserver.com/my_secure_document

Twilio will authenticate to your web server using the provided username and password and will remain logged in for the duration of the call. It is highly recommended that you use HTTP Authentication in conjunction with SSL. For more information on Basic and Digest Authentication, refer to your web server documentation.

Using SSL with Twilio

If your application exposes sensitive data, or is possibly mutative to your data, then you may want to be sure that the requests that hit your web application are indeed coming from Twilio, and not a malicious third party. To allow you this level of security, Twilio cryptographically signs its requests. Here's how it works:

1. Turn on SSL on your server and configure your Twilio account to use HTTPS urls.
2. Twilio assembles its request to your application, including the final URL and any POST fields (if the request is a POST).
3. If your request is a POST, Twilio takes all the POST fields, sorts them by alphabetically by their name, and concatenates the parameter name and value to the end of the URL (with no delimiter).
4. Twilio takes the full URL, with query string and all post parameters, and signs them using HMAC-SHA1 and your AuthToken as the key.
5. Twilio sends this signature in an HTTP header called X-Twilio-Signature

Then, on your end, if you want to verify the authenticity of the request, you can re-assemble the data string by going through the exact same process. If our two hashes match, then the request was authentic. You can then be sure that all the data used to construct the hash, including the full URL, query string and POST parameters were all sent to you by Twilio. Here's how you would perform the validation on your end:

1. Take the full URL of the request, from the protocol (http...) through the end of the query string (everything after the ?)
2. If the request is a POST, take all of the POST parameters and sort them alphabetically.
3. Iterate through that sorted list of POST parameters, and append the variable name and value (with no delimiters) to the end of the URL string
4. Sign the resulting value with HMAC-SHA1 using your AuthToken as the key (remember, your AuthToken's case matters!).
5. Base64 encode the hash
6. Compare your hash to ours, submitted in the X-Twilio-Signature header. If they match, then you're good to go.

Notes about SSL:

• Twilio cannot currently handle self signed certificates.
• Remember to keep your Twilio Auth Token secure.  It not only enables access to the REST API, but also to request signatures.

Please visit our documentation for SSL examples and more information on TwiML security.

Photo credit: AMagill

Don't Dial That Digit! Twilio Has Your Back

There are certain numbers that you probably don't want dialed with your Twilio-powered application, such as 911 (taking time away from legitimate emergencies) or 411 (costing you money).  Twilio will return a 21202 error "Phone number is a 'premium' number" whenever these numbers are dialed:

• 911
• 411
• (any x11 service)
• (XXX)-555-1212
• 900/976

Not only is this helpful for you, but it will enable you to rest assured that outbound applications where a number is specified by your end users won't be compromised by people trying to prank or call premium paid lines (toll lines) but putting something into the input box that they shouldn't.

So go ahead,put that phone number input form field on your website or inside your application with the confidence that Twilio will make sure your account doesn't dial these numbers!