Direct Inward Dialing (DID)

Direct Inward Dialing (DID) is a telephone service that allows a phone number to ring through directly to a specific phone at a business instead of going to a menu or a queue and needing to dial an extension. A phone number that is used like this is often called a "DID" (and multiple numbers are called "DIDs”).

There are 2 ways to get DID-like functionality with Twilio Phone Numbers, via a SIP trunk, and with SIP registration. 

DIDs with SIP Trunking

You can connect a Twilio SIP Trunk to your PBX. When a call comes in to Twilio to any of your phone numbers Twilio will send the call to your PBX over the SIP Trunk. Your PBX can then route the call to an extension based on the number dialed. 

DIDs over a SIP trunk

 

List the SIP configuration guides section of the docs to get step-by-step instructions. 

DIDs with SIP Registration

Using Twilio SIP Registration you can connect a call directly to a VoIP desk phone or soft phone. When a call comes in to Twilio to your phone number, Twilio will send it directly to your SIP registered endpoint. 

DIDs with SIP Registration

 

See documentation for registering a SIP endpoint on Twilio.