It was only a week ago that Microsoft (MSFT) offered users of older Apple (AAPL) iPads a $200 Microsoft Store gift card for turning in their “gently used” iPad 2, 3 or 4 units. Now the vendor has dangled more candy in front of users with a new Microsoft Corporate Buyback promotion for used Apple devices, Samsung gear, BlackBerry (BBRY) phones and stuff from other manufacturers, offering a $350 gift card toward the purchase of a Windows Phone, Surface tablet, Windows PC or notebook.

From the website, it’s unclear how long the new trade-in runs. In the earlier promotion, which runs through Oct. 27, the vendor is urging, but not requiring, users to trade in their old mobile gear for a Surface RT or Surface Pro, in a decks-clearing exercise prior to the launch of new Surface models Sept. 23 in New York.

The two offers are unrelated, wrote Jim O’Neil, Microsoft technology, evangelist, in a blog post.

“Trade in your old iPhone, iPad, BlackBerry, Samsung and dozens of other makes and models of phones and tablets, and get up to $350 back (via a prepaid Visa card) when you buy a Surface, Windows PC or laptop or Windows Phone,” said O’Neil.

In the corporate buyback promotion, users can trade in more than one device, O’Neil wrote. The new promotion is being done with Clover Wireless—which will assess the trade-in value of the used devices—and is aimed at business customers with stockpiles of tablets and phones but anyone can participate, he said. Clover decides what to do with the old devices—refurbish and resell them or donate them to charity.

“It is designed to incent commercial customers to move to the latest tablet and phone form factors,” wrote O’Neil.

Users can get a quote on the trade-in value of their used devices online where a list of eligible devices also is listed. The offer is not reserved to in-store exchanges. To work the promotion, users register online the devices they want to trade and are sent packaging material and mailing instructions. In exchange, users must buy a Microsoft device within 30 days and present the receipt to Clover, which, in turn, will send a rebate 30 days thereafter as a prepaid Visa card.