Twilio raises $12M to let you call a computer with telephone-to-web technology

Twilio, which provides software to connect phone calls to web applications, announced today that it has raised $12 million in its second round of funding to bring additional engineers on staff and continue marketing its services.

The San Francisco, Calif.-based startup provides developers with an application programming interface (API) that connects landline, voice-over-IP and wireless phone calls to Web applications. That could lead to a variety of uses — such as an online call center, or calling a database to find information.

Twilio then charges for the phone calls. It charges 1 cent each minute for inbound calls to a web application, and 2 cents for outbound calls from an app. Twilio also upgraded the service earlier this year to connect text messages to Internet applications. Outbound SMS messages cost 3 cents per message. Each dedicated Twilio phone number that connects to a web application costs $1 per month. Twilio also provides a number of other premium services, like text-to-speech and transcripts of phone calls.

Dave McClure’s 500 Startups firm is an investor in the most recent round of fundraising. That should come as no surprise, since Dave McClure is on the board of Twilio and is quite enamored with the service. He even started a $250,000 micro-fund for startups using Twilio’s API in September. Even prior to announcing the micro-fund, 500 Startups had already invested in startups using Twilio — including TeachStreet, HomeBoodle, and Mogotix.

The recent round of fundraising, led by Bessemer Venture Partners, brings Twilio’s total funding up to $16 million. That includes its first round of fundraising closed just about a year ago, which was worth around $4 million. Union Square Ventures also participated in this round of funding.

Twilio now has around 20,000 developers working on applications that include its API, according to TechCrunch. Its clients include Cheetos, Sony Music and Tumblr.