What is DID in VoIP?

DID stands for Direct Inward Dialing Number. A DID is used to designate direct calling lines accessible from external phones.

In the US, it is a ten-digit number broken up into a three-digit area code, a three-digit prefix, and a four-digit line number.

In the US, only lines that have a DID can have a unique e911 address. Remote workers need to have a DID to send their address to emergency services. Otherwise EMTs may show up to your office instead of their location.