Twimlets!
What are Twimlets?
Twimlets are tiny web applications that implement basic voice functionality. Think of them as "Widgets" in the web world.
You don't need to sign up to use them, they're just available for your use. And they're stateless, so you can just pass the URL parameters of execution in when you call them.
Twimlets are also open source, so if you'd prefer to download the code to your server, you can modify to suit your exact needs!
Using Twimlets
You can wire up a phone number (or an outgoing call) to the URL of one of these Twimlets.
You can also combine Twimlets with your own applications. You can redirect the call flow from your application into a Twimlet, using HTTP Location: header, or the <Redirect> verb.
You can also redirect back from a Twimlet into your application.
What Twimlets are Available?
Forward: will forward a call to another phone, and optionally forward to a new URL if the call isn't answered or the line is busy.
Find Me: will ring up to 10 phone numbers in order, until somebody answers the call, and forward to another URL (or Twimlet) if none of the numbers are answered.
Simulring will dial 2 or more (up to 5) phone numbers simultaneously, and the first person to answer is connected to the caller, and forward to another URL (or Twimlet) if nobody answers.
Voicemail will ask the user to leave a message, and will email the audio recording to a specified email address.
Simple Menu will play a message for the caller, and wait for them to press one or more digits, launching them to a new URL (or twimlet!) based on what they press.
Simple Message will play one or more audio files, say one or more text blocks, or any combination of both.
Call Me is a simple version of Simulring or Find Me that only rings one number, and forward to another URL (or Twimlet) if nobody answers.
Echo simply outputs TwiML passed in via the URL. Useful for building completely stateless apps that place outbound calls.
Conference allows you to build a simple conference line. The conference may be moderated, or may be open.
Hold Music plays hold music indefinitely, based on music stored in an S3 bucket.
Chaining Twimlets
Many Twimlets can be chained to another URL based on what happens during their execution. For example, if the FindMe Twimlet wasn't able to, well, find you... then it could forward to a voicemail Twimlet.