AT&T and APIs: Where Does Twilio Land?

Whose APIs is AT&T Running?

Disclaimer: I work as VP of Marketing for 2600hz, the free and open-source cloud telecom company. We work in the same space as Twilio and Voxeo, including APIs, but from an admittedly different vantage point.

News comes out today from AT&T that they will be unveiling a new API based on Voxeo’s Tropo system and Ericsson’s IMS implementation. This comes as a bit of a shock because it was only in October that Twilio announced their work with AT&T providing APIs as well. Dave Michels at Talkingpointz made an excellent point on this topic here, but I still have to know: What the hell is going on here?

Two Voice APIS?

Yes it’s true, AT&T will be offering two voice APIs, at least for the time being. The Twilio stack will be used to deliver applications external to the AT&T network and Voxeo’s Tropo stack will be used to deliver applications internal to the AT&T network. If you want to ring multiple phones from one phone number, use Tropo. If you want to capture digits and perform purchasing with an AWS based database, use Twilio. How did this happen? It’s really a tale of two cities.


Twilio had a philosophy that AWS was going to be their infrastructure and they’re going to willfully ignore other infrastructures. There are both pros and cons to this strategy, but it’s quite viable and nothing to sneeze at. The problem for Twilio is that no major Telecom runs in AWS. More precisely, all major carriers run their own proprietary and bizarre infrastructures and there was simply no integration point for Twilio to enter. Truthfully, Twilio can’t integrate with other carriers below the Web API Level, and the overhead of web requests (and relative insecurity) is too great a load for most Carriers. Contrast this with Voxeo.


Now Voxeo essentially WAS Twilio about 6 years ago. The young upstart Voice API company that famously raised a TON of money and then was repurchased by the original founders in a very interesting twist on the leveraged buyout. I’m not one to criticize financial maneuvering, but what the Voxeo guys pulled off was nothing short of Voodoo. So here you had Voice APIs but no real carrier integration. Recognizing this problem years ago, Voxeo built IMS integration for Tropo with all of the major IMS vendors. This is not a simple thing, it takes a lot of time, but the reward is huge. IMS is how applications get into carrier networks, it is the reason Voxeo won AT&T over Twilio. With IMS integration the Tropo stack can exist inside the AT&T firewall, which is something that Twilio can’t, or won’t, do.

What does this mean for Johnny Developer?

If you want to ring multiple phones use Tropo; if you are writing scripts, use Twilio. In the future, applications which use core AT&T services will be carried out over Tropo and Twilio will be relegated to only external applications, unless something drastic happens.

Huge win for Voxeo today, big blow to Twilio, in my humble opinion.