Workplace — Facebook’s bid to take on the Slack, Microsoft and the rest of the players in the market of business chat and collaboration — is getting a big push today by way of a significant customer win. The company has signed on Walmart, the retailing giant and the world’s biggest employer with 2.2 million employees on its books.

Walmart is rolling out Workplace to the whole of its business in stages, starting with associates and teams at Sam’s Club and other parts of the operation.

The move speaks to how Walmart — which last year acquired Jet.com for $3 billion — continues to step up its tech game as it feels the pinch of competition from Amazon, an e-commerce giant that is very quickly moving into Walmart’s brick-and-mortar territory.

“We believe the right technology can empower our people. Walmart’s vision of the future is centered around people — by serving the communities people live in and the people who work at Walmart,” said Clay Johnson, Walmart’s CIO and EVP. “Workplace shares this mission, and together we’re building the next generation workforce.”

Some of the uses so far for Walmart include to share pictures with other stores of a particular product display; to broadcast news via the Live video stream; and to manage communications between different geographies using Facebook’s automatic translation features (Walmart has operations across North America, South America, Europe, Africa and Asia).

For Facebook, the new customer comes at a time of steady growth for Workplace, an enterprise version of the social network designed specifically for use by teams and entire businesses. Workplace emerged from a closed beta about a year ago and has picked up some 14,000 businesses since.

Julien Codorniou, VP of Workplace, told TechCrunch that Facebook is not revealing what that translates to as a total number of users. Other customers include the likes of Starbucks (total employees: 254,000) and Telenor (37,000), although it’s not clear how many employees at these companies are actively using Workplace.

There are a lot of areas in enterprise software dominated by legacy players that are ripe for disruption by other companies using tech to do things differently and more efficiently (indeed, it’s a paradigm that Amazon is chasing very aggressively with its AWS division). But by virtue of being a relatively new concept, the same does not go for social networking in the enterprise world, yet.

In the case of Workplace, it’s competing for customers against the likes of Slack (which itself launched an enterprise tier earlier this year), Teams and Yammer (with the latter two from Microsoft), Chatter from Salesforce, Jive, and a slew of similar services of varying popularity, with new services launching seemingly every day (today’s launch: Cliq from Zoho).

Indeed, there is no single company dominating the market, with many players only emerging in the last five or so years. That means the field is wide open for a land grab, but also that there is still a lot of movement among customers.

Walmart, for example, also seems to be a customer of Slack’s. Its Walmart Labs division once was Slack’s largest customer, and as of my most recent sign-in attempts today — using two domains that I found on Reddit from people chatting about official Walmart Slack channels — there still seem to be Walmart accounts integrated with the platform. (And do not forget that Jet.com seems to credit Slack for helping it clinch its Walmart deal. It may not part ways so soon.)

Walmart would not comment on Slack directly.

“We use a variety of tools within the technology landscape,” said Dan Kneeshaw, a senior director of digital strategy and brand engagement at Walmart, in an interview. “We brought Workplace in to complement other tools that are being used.”

From what I understand, Walmart is still looking at the optimal way of distributing Workplace most widely. For now, both employees who are not using Walmart-issued devices, as well as those who are, are being given the option of using the Workplace app on their own devices, and using the app itself is not mandated.

Facebook and Walmart hope that there will be enough carrots to drive usage regardless. The interface of Workplace closely follows that of Facebook, which has been one of the key selling points for the service. For companies that have failed to get their employees to adopt and use other services, the pitch goes something like this: many people already use Facebook, so there is no learning curve with Workplace.

That might resonate especially with companies with a lot of employees who are not tied to desks and are not “knowledge workers” using a variety of other software all day long.

But in order to stay competitive with the likes of Slack — which has made a name for itself as an “operating system” by virtue of its hundreds of integrations and bots that let you interact with all the software your business uses — Facebook has also been expanding in Workplace’s functionality in more traditional IT ways.

It now offers integrations with larger software platforms from Box, Dropbox, Salesforce, Microsoft and Google. Earlier this year it also introduced enterprise compliance features, and in its wider bid to tap into tech being built for Facebook’s consumer products, it also introduced bots.

“We know what we do well, and what we don’t want to do,” Codorniou said. “Workplace is the communication layer, and we want to make sure that it’s integrated well with the other things businesses use.”

The service, subsequently, comes in a freemium plan. There is a basic, tariff-free tier that gives users features that are very similar to what you get on Facebook today, minus the ads: it includes communication tools like voice and video; single and group chat functionality; and unlimited photo storage.

The premium tiers, meanwhile, include all the integration features, admin controls, admin support, APIs and single sign-on, active directory support. They start at $3 per user for the first 1,000 active users; $2 for the next 9,000; and $1 for all above that. The premium service is free for non-profits and educational institutions.