Skype changed the way we communicate online by offering an easy and affordable way to call anybody on a land line or other Skype users. Microsoft bought Skype last year to pump money into the development of more Skype products. Enter Twilio, an API that allows anybody to build an app for cloud-based calling over land lines. Microsoft has entered into an agreement with Twilio to offer Windows Azure developers the Twilio APIs.

If you’re confused as to why Microsoft would go with somebody else over Skype, don’t be. Skype is proprietary software that isn’t suited for cloud-based apps. Twilio is a cloud-based API that’s going to facilitate the creation of apps over Windows Azure, a cloud-based app building and hosting platform like Google’s App Engine. It would take Microsoft and Skype some time to create a cloud-based API. Why build when you can just partner with a company already in the industry?

The deal has Windows Azure developers being able to take advantage of Twilio’s voice, SMS, VoIP and Phone Number APIs for cloud-based apps. Twilio’s main advantage is that it offers these services with small amounts of code. In fact, Twilio’s claim to fame is that it only takes three lines of code to implement voice calling in an app.

Twilio also has pretty fantastic rates. You don’t pay to use the API, but rather pay for the amount of minutes that people use on your app. It’s as low as one cent inbound and two cents for outbound calls. You can also create your own phone numbers which only cost a measly $1 a month. The service is already pretty popular among a large group of companies according to its customer list.

As TechCrunch points out, however, who uses Windows Azure? Sure, it’s a great service on par with Google’s App Engine, but I never see anybody talking about it except for Microsoft. Where’s all the praise, all the government and corporate endorsements? Will the offer of Twilio be enough to sway developers to start using Azure? Well, the companies are offering 1,000 texts or inbound minutes if you upgrade from a free account.

Will you switch to Windows Azure for Twilio? Or do you prefer another cloud-based Web application platform? Let us know in the comments.