How to call a voip phone?

[Energize]

How do you call a voip phone on a normal landline does the person with the voip phone have to be using a service like skype or can you dial an ip address?

 

[Duke]

AFAIK they need to register (pay) to get an actual phone number, so then you can call them like normal.

 

[HEADRAT]

Yep in terms of Skype its called SkypIn