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Voicemail for Hackers

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92 pointsTitanous24 comments

Say what you will about programming by gluing things together, but the fact that "answering the phone" and "doing voice recognition" are services that I can just use is amazing.

And a little light bulb just went off over my head. Now I know why patio11 is working on a Twillio app. There are so many cool things that could be done with this.

I think most of the "trying Twilio out" apps published barely scratch the surface of the potential, even though many are cool. (I did one, too: time-aware phone secretary, which has totally resolved my "My family does not understand that 3:30 AM Japan time is a bad time to call for a chat" problem.)

Because everything is on your web server, you can seamlessly move data between the phone and an arbitrarily complex web interface. I think that basic pattern allows multiple disruptive applications for any industry you care to name.

What are the big differences between Twilio and Tropo?

I'm the developer evangelist for Tropo. Here's a rundown of the big differences between Tropo and Twilio.

Tropo is 100% free for developers. No credits, no limits on minutes, no ads played to you or your callers. You even get your own phone number. You decide when you're ready for production and when you're ready to start paying.

Once you're in production, Tropo's SMS and toll free minutes are cheaper. Transcription is free with Tropo. Twilio's phone numbers are cheaper by a couple of dollars each. If you're going to have less than 150 minutes per month of usage or less than 200 text messages in a month, you'll save about a buck a month using Twilio.

Tropo has speech recognition. Instead of just "push 1 for this, push 2 for that" your callers can talk to your application.

Tropo is international. We have numbers in 30 countries, speech recognition and text to speech in 8 languages, and can send SMS worldwide. More languages and countries are coming.

Tropo is a unified API. No need for one app for voice, another for SMS and a third for conferencing. A single application can do all of that. The code you use to say something over the phone can also respond via SMS, IM, and Twitter.

Tropo is more than just phones. As mentioned above, we do all the major IM networks and Twitter too. No need to code to different APIs. Click a button and you have a Jabber bot. Or a Twitter bot. Or AIM. You get the idea.

Tropo's SMS supports short codes. If you want a shortcode for your application, let us know and we'll help you out with that.

Tropo offers a web services model where we post information about a call to your server and you reply with what you want us to do with the call. We also offer a scripting model where we've extended popular web scripting languages with built-in functions for communications. You run your code on our server for reduced latency.

Twilio can do some nifty things while you're in a call. They give you some REST apis you can hit to control sessions in progress. Voxeo's enterprise products have offered that for years, but it hasn't made it into Tropo yet.

Tropo lets you call your app via SIP and Skype. As mentioned elsewhere in this thread, that allows you to buy a number from any SIP provider and connect it to your application. It also allows you to forward your SIP PBX over to your application under certain conditions. Maybe you have an Asterisk box running your business. During off hours, forward to Tropo so your application can answer calls and give information to your callers.

Twilio lets you provision new numbers programatically. Tropo doesn't do that yet, but it's coming soon.

Tropo is built and hosted by telephony experts using the same platforms that power some of the largest companies in the world. Tropo is a product of Voxeo, a company that's been building voice platforms for over 10 years. We have data centers around the world that are optimized for voice. Your voice application isn't sharing space on an EC2 instance with somebody's web server.

Twilio's documentation is better. We're working on it, and in the meantime, our 24x7 support will answer your questions quickly. In most cases in less than an hour.

I'm sure that the Twilio folks have some additional thoughts on how they're different than Tropo. Instead of speaking for them too much, I'll let them reply.

Woah, that was longer than I intended. Sorry about the wall of text there.

Hi, I don't speak for Twilio but as a developer I've used their system quite a bit in the past and enjoyed it lots. Haven't yet used Tropo, but I think it's really interesting. Sorry for necroposting, but I just found this via search.

Twilio isn't indefinitely free for developing like Tropo, but they do give you $30 credit when you sign up, which goes a long way towards pre-production testing. Twilio can do international outbound calls, but as you say they don't yet have international inbound.

Twilio and Tropo both have a REST API. The main difference here is that you reply to Twilio with XML and Tropo uses JSON. Although proprietary, either one is easier to use than VoiceXML IMO.

Tropo has an amazing number of nice voices you can use to read off text to the caller. Twilio has just "male" and "female", last time I checked. On the other hand, correct me if I'm wrong, but I don't see where Tropo could play an MP3 to the caller, whereas there are lots of ways to play recorded music or messages to the caller with Twilio. As far as recording, you have to give Tropo a place to send recordings, whereas Twilio will store the recordings for you. Twilio also has tons of API methods to access data, like list all your recordings, call logs, and so on. I don't see that for Tropo.

Hmm, this is getting long. I think a comparison blog post is in order. I love the fact that there are at least two smart, highly motivated companies in this space. I hope Twilio and Tropo push each other to greatness.

To play an audio file in Tropo, just use the URL inside of your say() command. We'll recognize it automatically and do the right thing.

And you can store the recordings on Tropo -- your Tropo app space has FTP and WebDAV credentials, so you can tell your app to FTP it to Tropo's webhosting. We don't want to store your recording forever, but fell free to use it for short-term recordings.

Hi Akalsey,

Could you please answer Barnabas to clarify his miss understanding, because Tropo has great voices.

Thanks Joop

What advantage does this have over Google Voice, apart from GV's limited regional availability?

From my experience, google voice is quite buggy. Half the time i get "number doesn't exist" when i call a GV number. The speech-text is pretty bad too.

I'm Canadian, so that's a major reason why I wrote it. The other advantage is that you can do whatever you want when it comes to processing. For example you could send the recording via MMS to your phone.

This does a whitepages lookup, Google does not.

I was pretty impressed when my MagicJack sent me my phone message to my email, just audio though, no transcription.

You could have your Tropo app send you the audio file, too as an MP3 attachment.

Though the technology is impressive, I'm disappointed it's taken so long for it to reach the mainstream. Asterisk has been able to do this kind of thing forever, and I had a fax modem in the mid 90s that had voice capabilities and a programmable voicemail app included.

I wouldn't say it's taken this time to hit the mainstream. It's just experiencing a second wave of popularity. VoiceXML and it's predecessors were all the rage in the late 90s among the web developer crowd. Most of the automate phone systems you call at larger companies are VoiceXML backed.

One thing that has changed in recent past is that the cost has come down significantly, making voice apps accessible to smaller developers and hobbyists.

For those that want to use Asterisk and still take advantage of a web-centric programming model. Take a look at Adhearsion. It's an open source Ruby framework for writing Asterisk apps. Voxeo is a current sponsor of the project. http://adhearsion.com/

We do plan on implementing the Adhearsion API on Tropo, allowing someone to build a portable app that runs either on their own Asterisk server or on the Tropo cloud.

Is there a similar service/workaround that could be used in Europe? Tropo doesn't work in Europe, does it?

To solution is to get a local SIP DID from a company like Voip.ms and point it to Tropo's SIP URI. I mention this in the README.

https://www.tropo.com/pricing/

"International Phone Number" - "$10 per month"

Yeah, that will work. International SIP DIDs can also be had for around $4/month or less.

As noted by others, Tropo works worldwide. We've got numbers in 30 countries and 8 different European languages for text to speech. If you want a number in a place we don't list, let us know and we'll see what we can do.

Any plans for Asia?

We plan worldwide domination. :)

We already offer phone numbers in Japan. Some Asian countries don't allow voip services to operate or have extremely high costs. So it depends on where in Asia you're looking. From your Twitter profile, looks like you're in Singapore. We can get you a number there but they are fairly expensive. Feel free to send an email to Tropo sales or support and we can figure it out.

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