We are integrating a PBX to CM through a gateway using MGCP signaling. The gateway has a 4-FXS/DID card. I noticed when I was configuring the gateway in CallManager it had a mandatory field called "attendant DN". I thought digits could be passed incoming/outgoing of the FXS ports so what would the purpose of the "attendant DN" be?
Is it just one direction digits are passed? For example, from FXO to FXS or the other direction?
I have read different things about whether FXO/FXS supported sending digits through DTMF. I am confused if I really need the attendant DN in CM, however it is a mandatory field.