AT&T is retaining its partnership RingCentral and going a step further.

The companies announced Wednesday that they will expand the Office@Hand platform, much to the surprise of industry observers. AT&T had informed customers in January that it would part ways with RingCentral, whose Office platform is the foundation for Office@Hand.

AT&T now plans to offer the solutions to enterprise customers in addition to small and medium-size businesses.

AT&T’s Mo Katibeh

“Businesses of any size need connectivity and voice to improve their ability to compete. AT&T Office@Hand is flexible and easy to manage,” said Mo Katibeh, chief marketing officer of AT&T Business. “Working with RingCentral means we can deliver cloud communications and collaboration solutions to even more businesses to help their workforces be more productive, no matter where they are.”

AT&T originally launched the platform in 2012, calling it an “end-to-end cloud-based phone system.” Office@Hand works off a broadband connection and can be managed through computers, desk phones and mobile devices. AT&T offers three tiers of options for customers, accounting for the number of employees and features.

But the telecommunications giant in January announced the end of the line for the partnership. It planned to discontinue Office@Hand and transition customers using the service over to RingCentral, according to documents it provided to the Federal Communications Commission. The transition would take place over a year. It was a blow to to RingCentral, which would retain the existing customers but miss out on future AT&T accounts.

Now the agreement is back on, and AT&T will offer the platform to more than just SMB customers. The carrier wrote that it will target enterprise verticals that include financial services, health care and government.

“Through AT&T Office@Hand, we’re connecting more businesses with RingCentral’s innovative cloud communications and collaboration solutions, empowering them to communicate more effectively internally and externally,” RingCentral founder and CEO Vlad Shmunis said. “Now, AT&T’s business customers will have broad access to RingCentral’s industry-leading technology for greater business outcomes.”

Motley Fool’s Rick Munarriz writes that the recent renewal and expansion of the partnership is a win for RingCentral. It’s also a point scored against Cisco-owned BroadSoft, with which AT&T also does integrations.

“AT&T transitioning away from RingCentral wouldn’t have been fatal. It would’ve brought over corporate accounts that it could service and market other products to directly,” Munarriz said. “However, AT&T staying pat with RingCentral opens the door for a larger base of clients on its platform. The move also validates RingCentral as the best-of-class player in this niche.”

AT&T sells the solution directly and indirectly. This means members of AT&T Partner Solutions get to keep Office@Hand in their portfolio. Kevin Leonard, who leads AT&T’s Alliance Channel program, tells Channel Partners that his organization aims to help its solution providers reach businesses of all sizes.

AT&T’s Kevin Leonard

“We’re thrilled our solution providers will soon be able to offer their customers AT&T Office@Hand, based on RingCentral’s Office platform,” Leonard said. “Many of our indirect channel partners are familiar with the RingCentral portfolio and will be able to quickly ramp up with our new AT&T Office@Hand offer.”

We included AT&T and RingCentral in our recent list of 20 top UCaaS providers. In related news, AT&T scored a big win in the latest global Ethernet ranking, and RingCentral celebrated the fifth anniversary of it’s IPO.