Ericsson has agreed to buy Vonage Holdings Corp. in the U.S. for an equity value of $5.3 billion, in a major bid to build its presence in cloud communications services.

The takeover, if successful, will be Ericsson’s largest-ever deal, after its 1.2 billion pound ($1.6 billion) acquisition for Telent Ltd telecom equipment assets in 2005, according to data compiled by Bloomberg.

The Swedish telecommunications group will pay $21 per share for Vonage using existing cash, according to a statement. The offer represents an enterprise value of about $6.2 billion, according to a company statement on Monday.

The price Ericsson is paying for Vonage is “quite steep with an EV/Sales of almost 4.5x and an EV/EBITDA of c. 31x,” credit analysts at Danske Bank said in a client note.

Ericsson’s push into cloud-based services comes as its earnings have been hampered by both lost business in China and component shortages from a global supply-chain squeeze. The company said that it remains fully committed to its long-term Ebita margin target of 15-18%.

“Vonage gives us a platform to help our customers monetize the investments in the network, benefiting developers and businesses,” said Ericsson’s Chief Executive Office Borje Ekholm.

The U.S. company’s cloud-based communications platform accounts for 80% of its $1.4 billion annual revenues and enables developers to embed services such as messaging or video into their products. That customer base and developer community is seen as a key draw for Ericsson.

Ericsson’s activist owner Cevian Capital AB said it welcomed the company’s push to accelerate growth within the enterprise segment, enabling a “meaningful re-rating opportunity.”

Vonage itself had been under pressure from activist investor Jana Partners and was working with advisers to run a strategic review of the business. That review included the possibility of a full sale of the company, Bloomberg News reported in September.