It's hard to believe that an industry as traditional, as closed, and as controlled by large companies as telecommunications would be a ripe source for APIs for mashups. However, even Ma Bell (and now particularly Ma Bell's competitors) are rushing to enable powerful new services by publishing interfaces to their extensive, and incredibly expensive, infrastructures. Several interesting APIs are now available for messaging, call control and mobile applications. However, unlike most other web services APIs, expect to pay a small amount of money in transaction fees for using them.
In the world of telephones, call control refers to the part of the system that handles how calls are handled, when and what phones should start ringing. Two major versions of call control APIs are available to the intrepid developer: hosted and platform APIs. Hosted APIs are provided by existing telephone companies, and they typically handle all of the regulatory issues, equipment, etc. For instance, British Telecom has made major investments into providing an interface for application development onto their network. Internet companies as well, including AOL's AIM Phone line, allow you to write sophisticated telephone applications using their API. Smaller service providers, such as Phone Gnome, bet that their API will be the source of new and innovative applications that will drive minutes to their service. Hosted providers can also provide very specific services, such as Jaduka's API that lets you create calls between any two regular phones.
Platform APIs are provided by manufacturers of phone equipment, and allow you to control your own equipment with web services calls. For instance, LignUp makes a telephony switch with APIs specifically designed to enable Enterprise mashups.
Sylantro has a version more targeted towards carriers, with a carrier class system designed for medium to large installations of telephony services, with an API that not only includes call control and eventing, but also service provider issues such as provisioning and monitoring. In the open source world, Jay Phillips authored a Ruby on Rails plugin called Adhearsion that works seamlessly with Asterisk and Freeswitch.
The most ubiquitous computing platform on earth is not the PC, it's the phone. There's a saying that the only two things that people will turn the car around and go back home for are their wallets and their cell phones. Mobile APIs are a fast growing, and very exciting, part of the mashup world. 411Sync is a service that accepts text message requests, and returns a list of results to the phone based on a feed you give it. Mobile giant Vodafone's betavine API allows you to write location aware applications for the phone, perfect for location based applications such as search and advertising. Where's widget based approach makes developing location aware applications of Sprint/Nextel phones simple. Jaiku, like Twitter, provide APIs that extend blogging, presence and social networking to the mobile arena.
Messaging APIs provide a simple method to include text or SMS messaging into your application. Providers such as StrikeIron's SMS GlobalPro, Clickatell and aql all provide the ability for your application to send text messages to nearly any cell phone in the world for a small fee. Although sending text messages is quite simple to do, receiving them is a harder prospect, requiring the company to register a short code with the government, and to pay a monthly fee of around $1000.00 each month in the US.
The business models for the providers of telephony APIs are very simple: they typically charge you for their use, and normally on a per transaction basis. Nearly all mobile, messaging and telephony web services connect to the public switched telephone network (PSTN), that always charge something for connection. Providers of web services that connect to the PSTN must therefore also charge some access fee to the API users. Fortunately, these charges are typically fairly low, ranging from a few cents per minute for normal voice termination, to a little more than a dime for text messaging. Of course, nearly half of the planet has access to phones, so even though the access charge is a few pennies, those pennies add up.
Mashup developers have an equal chance of making money, as integrating messaging and voice communications with Enterprise applications is not only attractive to businesses, but also attractive to consumers. Enterprises are accustomed to paying for communications services, especially when the service saves money or creates a sustainable and provable competitive advantage. Consumer oriented business models for communications mashups have larger issues, as consumers tend to try to minimize the price they pay for any service. However, entertainment or social networking centered applications remain fertile areas for telephony mashups, and people seem willing to pay for them.
Telephony mashups may be the newest application segment on the block, but they present the best shot at providing sustainable revenue sources for those that write them. At the 2007 ETel show mashup competition, finalists RoboPhone, LignUp and the After Hours Doctor's Office could each be a sustainable commercial business. Twittervision has less of a business focus, but is certainly entertaining.