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.
Secondly you then dial the INTERNATIONAL DIALING CODE and this is the number that specifies which country you are dialing. So you are right to say that the international dialing code for the USA is '1' (it is also the same for Canada).Your phone company then routes the remaining digits you dial to the country the number represents.Now comes the interesting bit-why '1' for USA and larger numbers (Like '44' for the United Kingdom) for other coutries. Its all to do with how your phone company routes calls to other phone companies.o you are right to say that the international dialing code for the USA is '1' (it is also the same for Canada). Your phone company then routes the remaining digits you dial to the country the number represents.