T-Mobile USA this week introduced T-Mobile Wi-Fi Calling for Business, a new enterprise solution that allows business customers and their employees to make unlimited nationwide calls over Wi-Fi for just $10 a month.

Additionally, businesses with more than 100 lines of voice and data service may use BlackBerry smartphones from T-Mobile to receive free Wi-Fi calling nationwide and from abroad to the United States.

Business customers are allowed unlimited calling over Wi-Fi at work, home, locations within the T-Mobile HotSpot network or any ‘open’ Wi-Fi hot spot.

As a differentiator from traditional VoIP calling plans like Skype, which currently offers unlimited nationwide calling for $2.95 per month, T-Mobile notes that when customers leave work, home or exit a T-Mobile HotSpot network, their calls will transfer onto T-Mobile’s cellular network.

In addition to the Wi-Fi plan, T-Mobile also announced a partnership to deliver Research In Motion’s BlackBerry Mobile Voice System (MVS), which will be available to T-Mobile business customers in the coming months.

T-Mobile said it will integrate BlackBerry MVS as a key component of its enterprise offering. The new service will allow customers to replace the need for a desk phone with one of T-Mobile's Wi-Fi-enabled BlackBerry smartphones.