A virtual number can work like a gateway between traditional calls (PSTN) and VoIP.
Subscribers to virtual numbers may use their existing phones, without the need to purchase additional hardware, i.e. use the numerous available software.
The availability (and acceptable use) of virtual phone numbers are subject to the regulatory situation in the issuing country.
It is used to forward incoming calls to one or more pre-set telephone numbers chosen by the client.
They are also used for business purposes, as they allow companies to have a local presence in multiple locations without having to set up a physical office.