Microsoft is entering the next phase of its multi-part Skype for Business (Lync) rollout, with the launch of three new preview programs for its promised Skype for Business services.

Technical previews are launching on July 1 for three new services. To participate in the test programs, users must have an Office 365 Enterprise plan or a Skype for Business Plan 2.

The three:

Skype Meeting Broadcast enables users to broadcast of a Skype for Business meeting on the Internet to up to 10,000 people, who can attend in a browser. This service is for large virtual meetings like internal "Town Hall" style meetings and public webinars. This preview is available worldwide.

enables users to broadcast of a Skype for Business meeting on the Internet to up to 10,000 people, who can attend in a browser. This service is for large virtual meetings like internal "Town Hall" style meetings and public webinars. This preview is available worldwide. PSTN (Public Switched Telephone Network) Conferencing allows people invited to a Skype for Business meeting in Office 365 to join the meeting by dialing-in using a landline or mobile phone. This service also allows users to add others to a meeting by dialing-out. This preview is U.S. only at this time.

allows people invited to a Skype for Business meeting in Office 365 to join the meeting by dialing-in using a landline or mobile phone. This service also allows users to add others to a meeting by dialing-out. This preview is U.S. only at this time. Cloud PBX with PSTN Calling provides users with the ability to make and receive traditional phone calls in their Skype for Business client, and to manage these calls using hold, resume, forward and transfer. This preview is built on the enterprise voice technology available in Lync Server and Skype for Business Server, and runs on Azure. This preview is U.S. only at this time.

In the fall, Microsoft plans to make available Cloud PBX for customers worldwide, with a configuration option for customers to use existing on-premises phone lines for inbound and outbound calling. PSTN Conferencing and Skype Meeting Broadcast should be generally available before the end of calendar 2015, a spokesperson said.

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End users cannot sign themselves up for these previews. Instead, the trials :must be provisioned for the customer tenant by an Office 365 administrator," Microsoft officials said. "End users interested in trying the new services should contact their Office 365 administrator," says today's blog post.

Microsoft kicked off its Skype for Business rollout in April 2015. To date, the company has made available Skype for Business clients for Windows, the core Skype for Business service and its Skype for Business Server. Skype for Business clients for other operating systems are coming this summer, officials have said.

AT&T, BT, Colt, Equinix, Level 3 Communications, Orange Business Services, TATA Communications, Telstra, Verizon and Vodafone, will deliver direct connections to Office 365 Skype for Business customers later this year through Azure ExpressRoute for Office 365, officials also said today.