The DID Number is a number corresponding to a Spanish province (Madrid, Barcelona. Zaragoza, Sevilla, Bilbao, etc). Calls received on these numbers are diverted to any country.
In this way, you can own “virtual offices” in Spain without the caller knows what the destination of the call is.
You don’t need any special equipment (switchboard, systems, etc.), only a fix or mobile line where you receive calls.
The call cost to DID numbers is completely carried out by the caller and receiving calls is free for your company.