A DID number (also called DDI / virtual number) is a local telephone number in a selected area code that is forwarded to a landline,mobile, VoIP software or hardware, SIP, H.323, IAX, Skype or Google Talk anywhere in the world. For small businesses  operating internationally with limited resources and a limited budget presents a major challenge. To that end, the use of DIDs provides a multitude of advantages:

1. DIDs covering numerous destinations worldwide can be acquired online.
2. Through the use of a DID your customers will be able to call you at local call rates. This is particularly significant because it essentially eliminates the need for local representatives at every location and allows you to talk as much as you want at a reasonable monthly rate.
3. Operating a small business may require you to travel. You can change the forwarding destination of your DIDs, so you can still receive all of your calls when you’re on the road. The price of the DID will remains the same regardless of destination (mobile or landline) and you avoid paying the cellular companies’ excessive roaming rates.
4. You can receive calls to your different phone numbers on a single phone line, and able to answer more than one call simultaneously.
5. You will also be able to receive calls from those connected to the traditional PSTN network on your VoIP or Skype devices, making you more easily accessible.

In short, a DID is easy to set up, flexible, useful and cost effective. Using DIDs a small business can establish a global presence at minimal costs.

Note: This information was provided by the helpful people at DID World Wide, a leading global supplier of IP-based communications services including Direct Inward Dialing (DID) access solutions.