A virtual number, also known as direct inward dialing (DID) or access number, is a telephone number without a directly associated telephone line. Usually these numbers are programmed to forward incoming calls to one of the pre-set telephone numbers, chosen by the client: fixed, mobile or VoIP.
A virtual number can work like a gateway between traditional calls (PSTN) and VOIP.A virtual private number is a telephone number that forwards incoming calls to any of a number of pre-set telephone numbers. These are also called a follow-me number, a virtual telephone number.Usually a virtual telephone number can be set to forward calls to different telephone numbers depending on the time of day and the day of the week; for example, between 9 and 5 on working days incoming calls will be forwarded to one’s workplace, but in the weekends to one’s cellphone.
A toll-free telephone number or freephone number is a telephone number that is billed for all arriving calls instead of incurring charges to the originating telephone subscriber. For the calling party, a call to a toll-free number from a landline is free of charge.
The features of toll-free services have evolved as telephone networks have moved from electro-mechanical call switching to fully computerized stored program controlled networks.