Why do some VoIP services cost money, and why are some free?
A VoIP service can connect users not only with other VoIP customers but also with phone services that are offline, such as those that use traditional landline networks and wireless cell phone networks. For those calls, VoIP service providers must pay access fees to the landline and wireless operators. Those charges are passed along to VoIP customers. Calls that are between personal computers with VoIP service (Some VoIP providers offer free calls to some destinations).
A VoIP service can connect users not only with other VoIP customers but also with phone services that are offline, such as those that use traditional landline networks and wireless cell phone networks. For those calls, VoIP service providers must pay access fees to the landline and wireless operators. Those charges are passed along to VoIP customers. VoIP services that stay on the Internet–calls that are between personal computers with VoIP service–are free.