RIM announced the upcoming availability of the BlackBerry Bold 9700 with Wi-Fi Calling from T-Mobile.

It will be the first 3G-powered BlackBerry available through T-Mobile USA, and also the first smartphone from RIM that includes built-in support for both 3G connectivity and voice calls over Wi-Fi, according to T-Mobile.

WCell International has announched that its VoIP calling platform is now available for download on a variety of mobile operating systems, including BlackBerry, Java, Windows Mobile and Symbian.
The Hong Kong-based application for mobile devices is awaiting approval by Apple for listing in the iPhone App Store.

XCast Labs has extended its IP videomail services to BlackBerry devices.
Consumers and enterprise users who own a BlackBerry Curve, Pearl or Storm, are now able to receive video messages from anyone with a videophone or Softphone application.

Skype is now available for the iPhone - and will be coming to BlackBerry in May.
The VoIP app on the iPhone will only work over Wi-Fi and not 3G. It will allow iPhone subscribers to use phone numbers in their existing iPhone address book - without the need for duplicate lists.
As always, it allows free calls between Skype users and charges for calls to landlines or mobiles.
UPDATE: Since being released on Tuesday it has emerged that Skype on iPhone does works over 3G, despite being intended only for use with WiFi.

Truphone announced today that it is launching a Blackberry application that enables business users to make international phone calls from their devices at fixed line rates.
The company claims that the new Truphone Business app will reduce call charges by at least half.

Vyke has released a beta version of its Mobile VoIP software and service for Blackberry devices using RIM software.
The addition of the Blackberry software now means Vyke's VoIP solution is available on the three most used mobile operating systems in the enterprise market - Symbian, Windows Mobile and RIM.

The VoIP mobile software developer Truphone has launched a beta version of its iPhone app for RIM's BlackBerry 8801 and Curve devices.
While Truphone Anywhere for Blackberry only works on WiFi enabled BlackBerrys at the moment it will be rolled out for 3G at some point.