That Messenger will be subsumed into the Skype product is old news. Today, Microsoft detailed the calendar by which the company will shift the tens of millions of Messneger users to the communications platform that it spent north of $6 billion to acquire.

Microsoft declined to be more specific on the userbase of Messenger. However, it is more than willing to be explicit on just how large Skype has grown: it now has more has more than 280 million “monthly active users.”

The software giant will commence moving the Messenger userbase to Skype, sans the ability to say no, on April 8th. Clients that are English-based are up first for migration. The process will conclude with the what the firm described as “Brazilian Portuguese” on April 30th at the earliest.

Microsoft is moving in broad strokes to cut down on its product diversity in situations where there is overlap; just as Hotmail users will be shunted to Outlook.com, so too are Messenger users being transferred to Skype.

Given that Microsoft has failed to describe the Messenger userbase as ‘north of 100 million,’ its notes on its usership falling into the tens of millions range, it is all but obvious that the service has fallen below the 9 figure active user figure. However, the influx of Messenger users will provide a material boost to Skype.

Messenger has suffered, given that analysis, from a sharp usership contraction in the past few months. Microsoft felt safe describing the service as having more than 100 million active users as recently has November. Quite obviously, that figure is falling fast.

For fun, let us math:

Assuming a Messenger userbase of 80 million, assuming a 60% functional transfer in that six of out every ten moved users becomes active on the new service, Skype could grow by 17% overnight.

The headlines have been plain. As Cyrus Farivar at Ars Technica noted recently, following its growth, Skype now accounts for an equivalent of one third of “global phone traffic.”

Microsoft wants that portion to grow. Skype gets Messenger just as Microsoft got Skype. The following piece of this equation is just how loud the whining will be among Messenger users. We’ll see.

Top Image Credit: Chris Potter