Voice-over-IP provider Raketu on Wednesday rolled out a Windows Mobile version of its software for making cheap international calls on smartphones.

The downloadable application is intended for smartphones running the PPC2003, Windows Mobile 5, and Windows Mobile 6 operating systems. Raketu provides a Skype-like service that enables VoIP calls from computers and mobile devices.

The company has "free calling zones" in more than 40 countries where users can make free international phone calls. Users can purchase a $9.95, $24.95, or $49.95 package to prepay for minutes not included in the free zones, according to Raketu. In locations not covered by the free zones, Raketu charges a cheap calling rate, which varies by country.

The application also can be used to send text messages globally at low international rates and to send e-mail and instant messages.

Raketu said its Windows Mobile customers will get the same benefits as its "RakOut" computer-to-phone prepaid customers, who receive 1,200 free minutes each month when they dial from their PC to a landline or mobile phone.

Earlier this month, Raketu introduced a VoIP application for BlackBerry users. The BlackBerry application is Web-based app, so it doesn't require downloading or installing software on a smartphone, whereas the Windows Mobile app does. To use Raketu's service on a BlackBerry, users must point their Web browsers at BlackBerry.raketu.com.

Raketu isn't the only VoIP provider targeting smartphone users. IVR Technologies, a software developer specializing in IP services, also this month unveiled new applications for making affordable calls on Windows Mobile 6-based smartphones. The applications -- Smartphone Calling Card and Callback -- are add-on modules for Talking SIP, IVR's application, media, and billing server. They can be integrated into Windows Mobile smartphones to facilitate cheaper mobile long distance rates.