A virtual phone number is also called Direct Inward Dialling (DID) or access phone numbers. It is a telephone number but without a direct associated phone line. Generally, these phone numbers are programmed to forward calls to one of the pre-set phone numbers. These are called follow-me numbers, personal number or a virtual phone number. A virtual phone number works as a gateway between traditional PSTN phone calls and VoIP. Virtual numbers users might use their existing phone, without having to buy additional hardware, i.e. use the available software. Users can also set to forward calls from virtual numbers to different numbers depending on the day of the week and time of the day routing.