Facebook (s FB) is planning to un-friend mobile push-to-talk voice messaging app, Voxer. Facebook is suspending Voxer’s ability to look up and find friends on Facebook’s social graph within 48 hours. The reason given? Voxer is too competitive with Facebook’s social platform.

When contacted by us, Voxer CEO Tom Katis told GigaOM:

Facebook contacted Voxer to notify us that they would be blocking Voxer users’ ability to find and connect with their Facebook friends via Voxer. Facebook informed us that the change would occur in 48 hours. Facebook stated that they view our service, with its tens of millions of users, as a “competitive social network.”

“We were a bit taken aback because we never thought of them as competition,” said Katis. This is a body blow for the company as Facebook has been a growth and retention engine. While Katis tried to play it cool, the reality within the four walls of the company is quite different.

Katis said that unlike some other apps, he was just using the authorization aspect of Facebook’s platform. Voxer used Facebook’s login system to find a Voxer user’s Facebook friends who are also on Voxer. Unlike other apps, it didn’t post messages to one’s news feed.

Facebook has yet to confirm the ban and we are waiting for their response.

Voxer has been using Facebook’s login technology since its launch in May 2011, and today about a third of its “millions” of daily active members use Facebook to log in. The ban will start to impact the Voxer community within a day or so.

Facebook’s actions are worth noting, especially for other app developers, he said. “Basically if you are a company that uses Facebook’s platform, your access can be taken away in a somewhat arbitrary manner,” he pointed out. “It is a cautionary tale, if anything.” Katis’ comments are bolstered by the sequence of events that lead to this suspension of access. Take a look and be the judge:

• January 3, 2013: Facebook introduced voice messaging to Facebook Messenger.
• January 16, 2013: Voxer introduced its Android app. (Katis told us the Android app release has significantly increased messaging in the days following the release).
• January 17, 2013: Facebook announced VOIP calling via Facebook Messenger.

I don’t know about you, but I can’t help but notice the correlation between Facebook’s product upgrades and this decision. It is not clear if the decision to ban Voxer was just applicable to Voxer or if it will be extended to other apps such as Wechat and Kakao. What about Skype?

To be honest, Facebook’s response shouldn’t come as a surprise. Having seen Instagram and Pinterest turbo-charge their growth by using Facebook’s open graph, the world’s largest social network has decided that it will never let anyone get big by using its graph as a crutch. When it saw Snapchat explode and it came up with its xeroxed version: Poke.

These actions remind me of the days when Microsoft (s MSFT) would use its influence to crush hit apps on its platform and come up with their own substandard version of that app. Maybe it is time for antitrust heavyweights to take out a clean blotter and start making notes.