Skype is getting its biggest face-lift in years, ditching its light-blue theme for a customizable interface and features aimed at the way young people communicate, from emojis to a Snapchat-like recap of the day.

In addition to the cosmetic changes being made by Microsoft, the update modernizes Skype's underlying infrastructure, years in the making, in an effort to give the service the reliability needed to compete with upstarts in the crowded world of communications software.

Amritansh Raghav, the corporate vice president who leads Skype, calls the update rolling out on Thursday, the biggest set of changes to Skype since the addition of video calling 11 years ago.

The service's former backbone -- peer-to-peer connections that linked a caller to their target through a direct line -- is being replaced in the update by Microsoft's network of data centers. Some of users' complaints about the service, including phantom notifications or calls that were missed entirely, should disappear as the service debuts for Skype's users, Raghav said.

"We needed to modernize the Skype infrastructure," he said. "The good news is we're finally done."

Skype, which Microsoft scooped up for $8.5 billion in 2011, was a pioneer in voice and video calls made over the internet, instead of wired telephone connections or cellular networks.

Today, such internet communications tools are commonplace, and some have lapped Microsoft's product in usage, partially a result of the Redmond company's small presence on smartphones.

Facebook Messenger and Facebook-owned WhatsApp each boast more than one billion users. China-focused QQ and WeChat aren't far behind, and Google and Apple are both investing in communications tools tied to their expansive mobile platforms.

A year ago Microsoft said Skype had 300 million "monthly connected users," little changed from 2013.

Thursday's update follows a corporate restructuring and layoffs as Microsoft consolidates what used to be Skype's broad European footprint.

Skype, formerly housed in Microsoft's Applications and Services Group, was moved in September after longtime engineering executive Qi Lu left the company. The engineering team shifted into the newly minted Office product group and Gurdeep Pall, the executive in charge of Skype, left that role.

He has since taken a position building software for businesses using machine learning tools, the company says.

Meanwhile, Skype development offices in London and Stockholm were shuttered, cuts that brought layoffs of more than 320 people, according to reports at the time. The company declined to comment on the size of the layoffs, and said Microsoft was trying to reduce Skype's geographical footprint and bunch software-engineering teams closer together.

Skype's remaining development offices are in Estonia, the Czech Republic, the San Francisco Bay Area, and Microsoft's Redmond headquarters.

In addition to the new Snapchat-like "Highlights" feature that compiles recent photos and videos into a shareable reel, the update places greater emphasis on tools to find friends and quickly fires off emojis or reactions in response to chats and videos.

Automated chatbots, a push by Microsoft as it aims to build more intelligent software, have been given a prominent home in the new Skype. Through a text window, users can summon Expedia to search for flight prices, or ask StubHub about concert tickets. But that functionality remains limited, and many software developers are only now getting their hands on the tools to make such Skype bots.

Raghav said the aim was to position Skype not as a social network, but as a tool to communicate with your close contacts in a more personal way.

"What differentiates (services) is not feature A or feature B, it's the network that you have," Raghav said. "We like the fact that Skype has been known not just as a social network, but the most personal of connections."

The update will go out in waves beginning Thursday, first targeting mobile devices running Android and, afterward, iOS. The software is expected to make its way to the desktop edition this summer.

Skype's workplace cousin, Skype for Business, isn't affected by the change.