Skype plans to deliver new Skype for Business voice and meetings capabilities in Office 365.Today 2nd/July/2015 Skype announced that customers of Office 365 enterprise could register for the new features mentioned below. The new capabilities will enhance the existing Skype for Business experience, and allow us to offer a complete, enterprise-grade communications solution at global scale as part of Office 365.

Ability to conference with over 10,000 people:
Customers with office 365 will be able to broadcast about any type of business meeting or conference online. The feature is integrated with Bing Pulse, for real-time polling and sentiment tracking, and Yammer, to enable attendee dialogue during the broadcast.

Join a meeting through your landline or mobile phone.
With skype PSTN conferencing feature you can join a business meeting by dialing in using a landline or mobile phone if your office 365 customer in areas without internet in U.S.
PSTN Conferencing in Office 365 will also allow people to add others to a meeting by dialing out.

Cloud PBX with PSTN Calling.
Available in preview to Office 365 customers in the U.S., provides people the ability to make and receive traditional phone calls in their Skype for Business client, and manage these calls with features like hold, resume, forward and transfer. This preview is built on the proven enterprise voice technology available in Lync Server and Skype for Business Server. Later this year, we will ship Cloud PBX for customers worldwide, with a configuration option for customers to use existing on-premises phone lines for inbound and outbound calling.

According to Zig Serafin, corporate vice president for the Skype for Business team, the new services will bring traditional calling and conferencing into the new era of workplace communications, and also add an entirely new way of communicating at much higher scale with much greater flexibility over the Internet.
For more see demo video https://youtu.be/wLWpAEH2cyI