Telecommunications enabler Twilio has raised a $100 million series E round that values the company at over $1 billion, according to government filings.

The news was first reported in Forbes, citing research firm VC Experts, which uncovered a Delaware filing revealing the large round. VC Experts confirmed the round and provided us with the documents, which indicate a price of $11.31 per share for the series E. With 8.8 million series E shares authorized, that means the company has raised — or is about to raise — a few pennies short of $100 million.

According to the Forbes report, this more than doubles Twilio’s total capital raised: It had previously raised $103 million in four rounds, the most recent of which was a $70 million series D in June, 2013. The lead investors in that round were Bessemer Venture Partners, Draper Fisher Jurvetson, and Redpoint Ventures. The most recent round also reportedly doubles the company’s valuation, from $500 million, putting it in the “unicorn club” (a term for venture-backed companies worth more than $1 billion).

When we last spoke with Twilio chief executive Jeff Lawson, he told us that the company hit an annual run rate of $100 million in revenue in 2014, and was adding $1 million in annualized revenue every seven days. That’s a tricky figure, because run rate assumes current revenues will continue at the same pace for the next 12 months, but it’s a metric frequently used by private companies as an indication of momentum.

Twilio has built a suite of services used by developers to integrate telephone capabilities into their apps, from placing a call to sending text messages. As part of that suite of services, it operates an extensive telephony network of its own, in order to connect its customers’ apps to telephone networks all over the world. It added video calling services to that suite in March.

Updated May 5 with confirmation from the Delaware document filings.