An example of a different type of softphone is Skype's softphone feature. Of all softphones, Skype is the most popular, with hundreds of millions of users worldwide, claims About.com. Another type of softphone is Gizmo, which shares a lot of similar services with Skype, including a softphone and paid service.
A good free softphone service is VoIPStunt, which offers free calls to mobile phones and landlines in a variety of countries. It is a competitor to Skype and Gizmo, and offers rates that are on the lower end of the softphone spectrum. Another reputable softphone is Yeigo, which is one of the best services for mobile phones, as stated by About.com.