Skype users can now make free SkypeOut calls to traditional landline and mobile phones in the U.S. and Canada until the end of the year. Skype calls made between PCs are free as before.

The free SkypeOut promotion comes at a time when competitors such as Yahoo and AOL are integrating more call features into their instant-messaging clients.

Tomorrow, AOL will announce the launch of AIM Phoneline service that provides a free local phone number to any AIM user for receiving free incoming calls. But it charges a monthly fee to make calls to regular phones or cell phones.

Related: China Firewall blocks Skypeout