Yahoo is to activate Internet phone capabilities for Yahoo Messenger users in the US, a little over three months after announcing this feature.

Since December, Yahoo has been doing a staggered rollout of the feature, which is now available for German, French, Spanish, Italian and Singaporean users.

By enabling it in the Yahoo Messenger client software for the US, the capabilities become effectively available globally, said Brad Garlinghouse, Yahoo's vice president of communications products. With this move, Yahoo is trying to get a piece of the hot Internet phone market, which is led by Skype.

The upgrade to the instant messaging service, called Yahoo Messenger with Voice, lets users dial out from the IM interface to traditional or mobile phones. Yahoo Messenger users are also able to rent one or more phone numbers from Yahoo to receive phone calls through the IM interface.

Calls made to phone numbers in the US. and 30 other countries with heavy telecommunications traffic will cost $0.02 per minute or less. Calls can also be made to over 150 other countries. Rates vary and are based on the place where the call terminates.

For US$2.99 per month or $29.90 per year, users will be able to obtain one or more phone numbers to receive calls from regular or mobile phones via their Yahoo Messenger interface. Initially, only US, UK and French numbers will be available.

Yahoo Messenger with Voice will also features a free voice-mail service, and for the first time adds a banner ad in the IM interface that will be "unobtrusive," Garlinghouse said. It uses the Global IP Sound GIPS VoiceEngine technology to process audio.