Unify Square, a startup that helps businesses implement Skype for Business, secured another $4 million in funding in a round led by Microsoft. 

This brings the total of an extended Series B round that started in February to $12.2 million. In addition to Microsoft, Stanford University and the tech-focused Bridge Bank of San Jose, Calif. participated in the round, along with former executives from IBM, Yahoo and Ariba.

According to a company statement, the funds will be used to enhance software, services and support for some 5 million customers.

Unify Square, a Microsoft partner, delivers on-premises and Software-as-a-Service (SaaS) products to architect Skype for Business infrastructure.

Before Unify Square, company CEO Sonu Aggarwal was key architect for Office Communications Server (OGS) at Microsoft, and drove engineering execution from requirements through delivery while acting as Group Program Manager.

When the Series B began last February, Unify Square noted it planned to expand its services globally and increase support. It also claimed it would bring innovations to the market and strengthen its channel presence among large systems integrators and other Microsoft ecosystem partners.

Based in Bellevue, Wash., Unify Square has raised $26.2 million since 2007 and employs slightly less than 100 people worldwide.