Its overlay area code is the 289 area code. It was introduced to the public in the middle of 2001. The first Mississauga (Malton) area code was all used up in the later months of 2005, thus the 289 area code will become the area code of phone numbers that will be given starting from that time onwards.
Direct inward dialing (DID), also called direct dial-in (DDI) in Europe and Oceania, is a telecommunication service offered by telephone companies to subscribers who operate a private branch exchange (PBX) system.
Answer     DID stands for Direct Inward Dial. Also know as DDI, Direct Dial In. It is when a phone on a private telephone switch can be dialled directly from a â¦ ny phone in the world. The last few digits of the number dialled are know as the DID number. For example, a telephone extension number 4400 might be dialable from anywhere as +35318784400. 8 people found this useful.