The german phone code 02166 represents Mönchengladbach-Rheydt in Nordrhein-Westfalen.
Note for calls from abroad: In addition to the German country code (+49 or 0049) you can omit the foregoing zero of the dialling code for Mönchengladbach-Rheydt. So you can dial +492166... and add the number of the phone line you want to reach.