olemus
sideteenus, mis võimaldab helistada välisliinilt
kodukeskjaama kaudu otse asutuse sisenumbrile
=
a feature that allows extensions in a company to have their own direct telephone number

ülevaateid
https://www.techopedia.com/definition/26021/direct-inward-dialing

https://en.wikipedia.org/wiki/Direct_inward_dial

https://www.3cx.com/pbx/did/

https://www.cisco.com/c/en/us/support/docs/routers/2600-series-multiservice-platforms/15268-vic-2did.pdf