The german phone code 07755 represents Weilheim (Kreis Waldshut) in Baden-Württemberg.
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 Weilheim (Kreis Waldshut). So you can dial +497755... and add the number of the phone line you want to reach.