The german phone code 02535 represents Sendenhorst-Albersloh 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 Sendenhorst-Albersloh. So you can dial +492535... and add the number of the phone line you want to reach.