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This video Explains the differences between DNIS and DID and how DNIS/DID and ANI work.

DNIS stands for Dialed Number Identification Service
DID stands for Direct Inward Dial
ANI stands for Automatic Number Identification.

DNIS is a telephone service that identifies for the receiver of a call the number that the caller dialed. It's a common feature of 800 and 900 lines. If you have multiple 800 or 900 numbers to the same destination, DNIS tells which number was called. DNIS works by passing the touch tone digits to the destination where a special facility can read and display them or make them available for call center or other programming.

DID allows you to dial someone using a private phone system (PBX) that can automatically ring their extension directly without being transferred by an operator. A DID system can be used for fax and voice mail as well as for live voice connections. Compared to regular PBX service, DID saves the cost of a switchboard operator, calls go through faster, and callers feel they are calling a person rather than a company.

As you can see, there can be some overlap between DNIS and DID. Depending on your specific telephony infrastructure, your telephony carrier may need to configure routing functionality in order to route DNIS digits dialed to the DID extension correctly in order for a RightFax server to be able to gather these digits to correctly route a fax to the proper recipient.

To configure routing via DID, for each user that should be assigned a routing code, in Enterprise Fax Manager under the User
Edit option, on the Routing tab, in the Routing Code box, you can enter the partial or complete digits for DID/DNIS phone extensions based on how many digits you are configuring in the "Number of Digits For Routing" in the DID settings of the RightFax DocTransport Module service.

Finally, ANI allows the called party to see the number that the caller provides as the number that they are dialing from (it is the digital equivalent of caller id on your home phone for businesses). ANI is configurable by the sender and as such it is an unreliable method for any type of inbound call control. Any sent ANI data can be viewed in the ALT+F10 Fax Information dialog applet from FaxUtil and is listed as the VALUE in the ANI property. Note also that Fax Information dialog here also lists the Fax DID Number provided to the server as well.

As always if you have any questions about this topic or any topic in the world of faxing let us know at The Fax Guys, we are always happy to help.

This is Jay with RightFax University saying thank you for watching and Please visit us again. The RightFax University is a work under continual progress and we update often.